TeraPHY Chiplet Optical Input/Output System

ABSTRACT

An electro-optical chip includes an optical input port, an optical output port, and an optical waveguide having a first end optically connected to the optical input port and a second end optically connected to the optical output port. The optical waveguide includes one or more segments. Different segments of the optical waveguide extends in either a horizontal direction, a vertical direction, a direction between horizontal and vertical, or a curved direction. The electro-optical chip also includes a plurality of optical microring resonators is positioned along at least one segment of the optical waveguide. Each microring resonator of the plurality of optical microring resonators is optically coupled to a different location along the optical waveguide. The electro-optical chip also includes electronic circuitry for controlling a resonant wavelength of each microring resonator of the plurality of optical microring resonators.

CLAIM OF PRIORITY

This application claims priority under 35 U.S.C. 119(e) to U.S.Provisional Patent Application No. 62/981,726, filed on Feb. 26, 2020,the disclosure of which is incorporated herein by reference in itsentirety for all purposes.

BACKGROUND

To date, optical communications have targeted pluggable and discreteform factors. Some of the form factors of the optical modules arestandardized, such as the QSFP28 or QSFP-DD form factors, and are fartoo large to achieve the density needed for chip input/output (I/O).Although recent attempts to bring optics closer to the connected hostASIC (application-specific integrated circuit), such as the on-boardform factors explored by COBO (Consortium for On-Board Optics), havemotivated tighter form factors, the types of optical devices andintegration methods used in contemporary optical transceivers are notsuitable for chip I/O, both from a size and power perspective. It iswithin this context that the present invention arises.

SUMMARY

In an example embodiment, an electro-optical chip is disclosed. Theelectro-optical chip includes an optical input port located on a firstside of the electro-optical chip. The electro-optical chip also includesan optical output port located on the first side of the electro-opticalchip. The electro-optical chip also includes an optical waveguide thathas a first end optically connected to the optical input port. Theoptical waveguide also has a second end optically connected to theoptical output port. The optical waveguide includes a first segmentextending in a first direction. The optical waveguide also includes asecond segment that extends from the first segment and that turns fromthe first direction to a second direction that is substantially oppositeof the first direction. The optical waveguide also includes a thirdsegment that extends from the second segment in the second direction.The first, second, and third segments collectively form a substantiallyU-shaped portion of the optical waveguide. The electro-optical chip alsoincludes a plurality of optical microring resonators positioned alongthe first segment of the optical waveguide. Each microring resonator ofthe plurality of optical microring resonators is optically coupled to adifferent location along the first segment of the optical waveguide. Theelectro-optical chip also includes electronic circuitry for controllinga resonant wavelength of each microring resonator of the plurality ofoptical microring resonators.

In an example embodiment, an electro-optical chip is disclosed. Theelectro-optical chip includes an optical input port located on a firstside of the electro-optical chip. The electro-optical chip also includesan optical output port located on the first side of the electro-opticalchip. The electro-optical chip also includes an optical waveguide thathas a first end optically connected to the optical input port. Theoptical waveguide also has a second end optically connected to theoptical output port. The optical waveguide includes a first segmentextending in a first direction. The optical waveguide also includes asecond segment that extends from the first segment and that turns fromthe first direction to a second direction that is substantiallyperpendicular to the first direction. The optical waveguide alsoincludes a third segment that extends from the second segment in thesecond direction. The optical waveguide also includes a fourth segmentthat extends from the third segment and that turns from the seconddirection to a third direction that is substantially opposite of thefirst direction. The optical waveguide also includes a fifth segmentthat extends from the fourth segment in the third direction. The first,second, third, fourth, and fifth segments collectively form asubstantially C-shaped portion of the optical waveguide. Theelectro-optical chip also includes a plurality of optical microringresonators positioned along the third segment of the optical waveguide.Each microring resonator of the plurality of optical microringresonators is optically coupled to a different location along the thirdsegment of the optical waveguide. The electro-optical chip also includeselectronic circuitry for controlling a resonant wavelength of eachmicroring resonator of the plurality of optical microring resonators.

In an example embodiment, an electro-optical chip is disclosed. Theelectro-optical chip includes an optical input port located on a firstside of the electro-optical chip. The electro-optical chip also includesan optical output port located on a second side of the electro-opticalchip. The electro-optical chip also includes an optical waveguide thathas a first end optically connected to the optical input port. Theoptical waveguide also has a second end optically connected to theoptical output port. The electro-optical chip also includes a pluralityof optical microring resonators positioned along the optical waveguide.Each microring resonator of the plurality of optical microringresonators is optically coupled to a different location along theoptical waveguide. The electro-optical chip also includes electroniccircuitry formed alongside the plurality of optical microring resonatorsfor controlling a resonant wavelength of each microring resonator of theplurality of optical microring resonators.

Other aspects and advantages of the invention will become more apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a vertically exploded view of an example multi-chip package(MCP) assembly, in accordance with some embodiment.

FIG. 2A shows an example block-level architecture of a systemimplementing a TeraPHY chiplet, in accordance with some embodiments.

FIG. 2B shows a vertical cross-section diagram of the substrate of FIG.2A, in accordance with some embodiments.

FIG. 2C shows interconnect metrics versus reach tradeoffs for variouselectrical and electro-optical semiconductor chip technologies,including the TeraPHY chiplets discussed herein, in accordance with someembodiments.

FIG. 3 shows an example organizational diagram of the TeraPHY chipletreferenced herein, in accordance with some embodiments.

FIG. 4 shows an example layout of the TeraPHY chiplet, in accordancewith some embodiments.

FIG. 5A shows a top view of a semiconductor wafer on which many TeraPHYoptical I/O chiplets are fabricated, in accordance with someembodiments.

FIG. 5B shows a scanning electron microscope (SEM) image of a portion ofthe TeraPHY optical I/O chiplet, in accordance with some embodiments.

FIG. 6A shows an example layout of photonic structures of the TeraPHYoptical I/O chiplet, in accordance with some embodiments.

FIG. 6B shows the example FAU for connection to the TeraPHY optical I/Ochiplet, in accordance with some embodiments.

FIG. 6C shows a close-up layout view of a set of optical gratingcouplers for a given optical macro corresponding to an optical portregion as shown in FIG. 6A, in accordance with some embodiments.

FIG. 6D shows a close-up view of the optical grating couplercorresponding to a region as shown in FIG. 6C, in accordance with someembodiments.

FIG. 7 shows an example layout of a given optical macro, in accordancewith some embodiments.

FIG. 8A shows a diagram of a first computer system optically connectedto a second computer system through an optical link, in accordance withsome embodiments.

FIG. 8B shows a more detailed view of the optical connections betweenthe TeraPHY optical I/O chiplet of the first computer system and theTeraPHY optical I/O chiplet of the second computer system, in accordancewith some embodiments.

FIG. 9 shows an example optical path layout of an optical macro for datainput/output to/from the TeraPHY optical I/O chiplet, where the opticalpath layout includes a U-shaped optical waveguide, in accordance withsome embodiments.

FIG. 10 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes a C-shaped optical waveguide, in accordancewith some embodiments.

FIG. 11 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes a C-shaped optical waveguide, in accordancewith some embodiments.

FIG. 12 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes a C-shaped optical waveguide, in accordancewith some embodiments.

FIG. 13 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes a substantially linear-shaped opticalwaveguide with corresponding optical ports located on opposite sides ofthe optical macro, in accordance with some embodiments.

FIG. 14 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes an S-shaped optical waveguide, inaccordance with some embodiments.

FIG. 15 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes a Z-shaped optical waveguide, in accordancewith some embodiments.

FIG. 16 shows an example optical path layout of an optical macro fordata input/output to/from the TeraPHY optical I/O chiplet, where theoptical path layout includes a hook-shaped optical waveguide, inaccordance with some embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide an understanding of the present invention. It will beapparent, however, to one skilled in the art that the present inventionmay be practiced without some or all of these specific details. In otherinstances, well known process operations have not been described indetail in order not to unnecessarily obscure the present invention.

Monolithic integration of electronics and optics, includingimplementation of microring-based optical devices, enables much tighterintegration of optical components and devices with integrated circuitchips at a far lower power requirement. The combination of integratedcircuit technology and photonics technology enables in-package opticalI/O with different floorplans and provides a roadmap for addressing thechip I/O challenge. Embodiments are disclosed herein for variouslayouts, organizations, and floorplans of electronic-photonic macros foran integrated photonic input/output (I/O) chiplet, such as the TeraPHYchiplet provided by Ayar Labs, Inc. of Santa Clara, California.

FIG. 1 shows a vertically exploded view of an example multi-chip package(MCP) assembly 100, in accordance with some embodiment. The MCP assembly100 includes an MCP 101 and a lid 103 disposed over the MCP 100, with athermal interface material (TIM) 105 disposed between the MCP 101 andthe lid 103. In some embodiments, the MCP 101 includes multiple TeraPHYoptical I/O chiplets 107A and 107B, and an integrated circuit chip 109.In some embodiments, the TIM 105 is disposed over the multiple TeraPHYoptical I/O chiplets 107A, 107B and the integrated circuit chip 109. Thelid 103 is configured to encapsulate the multiple TeraPHY optical I/Ochiplets 107A, 107B and the integrated circuit chip 109. In variousembodiments, the integrated circuit chip 109 is either a system-on-chip(SoC) processor, an ASIC chip, a field programmable gate array (FPGA)chip, or essentially any other type of integrated circuit chip. Invarious embodiments, the multiple TeraPHY optical I/O chiplets 107A,107B are co-packaged with the integrated circuit chip 109 using avariety of technologies (including, but not limited to, organicsubstrate, 2.5 D integration—Si interposer, embedded interconnectbridge, high-density build-up fanout, etc.) corresponding to the type ofelectrical I/O interface for the integrated circuit chip 109. TheTeraPHY optical I/O chiplets 107A, 107B are designed to adapt to theelectrical I/O interface of the integrated circuit chip 109, so as tooptimize I/O bandwidth density, energy efficiency, and packaging costsfor a given application. Each of the multiple TeraPHY optical I/Ochiplets 107A and 107B is configured to optically couple with acorresponding optical fiber array 111A and 111B, respectively.

FIG. 2A shows an example block-level architecture of a system 200implementing a TeraPHY chiplet 107, in accordance with some embodiments.The system 200 provides a general representation of any type of MCPreferred to herein that is implemented to include the TeraPHY chiplet.The system 200 includes the TeraPHY chiplet 107 attached to a substrate201. The TeraPHY chiplet 107 includes an optical interface that isoptically connected to an optical link 203 through which bi-directionaloptical data communication is performed with another electro-opticdevice, such as with another TeraPHY chiplet. The system 200 alsoincludes one or more integrated circuit chips 205 (semiconductor chips)attached to the substrate 201. In various embodiments, the one or moreintegrated circuit chips 205 includes one or more of a centralprocessing unit (CPU), a graphics processing unit (GPU), a visualprocessing unit (VPU), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA), a memory chip, an HBMstack, an SoC, a microprocessor, a microcontroller, a digital signalprocessor (DSP), an accelerator chip, and/or essentially any other typeof semiconductor chip. In various embodiments, the substrate 201 is anorganic package and/or interposer. In some embodiments, the substrate201 includes electrical connections/routings 207 between the TeraPHYchiplet 107 and the one or more integrated circuit chips 205. In someembodiments, the electrical connections/routings 207 are formed within aredistribution layer (RDL) structure formed within the substrate 201. Invarious embodiments, the RDL structure is implemented in accordance withessentially any RDL structure topology and technology available withinthe semiconductor packaging industry. Some of the electricalconnections/routings 207 within the substrate 201 are configured andused to provide electrical power and reference ground potential to theTeraPHY chiplet 107 and to each of the one or more semiconductor chips205. Also, some electrical connections/routings 207 within the substrate201 are configured and used to transmit electrical signals that providefor bi-directional digital data communication between the TeraPHYchiplet 107 and the one or more semiconductor chips 205. In variousembodiments, digital data communication through the electricalconnections/routings 207 between the TeraPHY chiplet 107 and the one ormore semiconductor chips 205 is implemented in accordance with a digitaldata interconnect standard, such as the Peripheral ComponentInterconnect Express (PCIe) standard, the Compute Express Link (CXL)standard, the Gen-Z standard, the Open Coherent Accelerator ProcessorInterface (OpenCAPI), and/or the Open Memory Interface (OMI), amongessentially any other digital data interconnect standard.

The system 200 also includes an optical power supply 209 opticallyconnected to supply continuous wave laser light of one or morecontrolled wavelengths to the TeraPHY chiplet 107. In some embodiments,the optical power supply 209 is a SuperNova multi-wavelength, multi-portlight supply provided by Ayar Labs, Inc. The optical power supply 209supplies continuous wave (CW) light that optically powers the TeraPHYchiplet 107. In some embodiments, the optical power supply 209 isconfigured as a photonic integrated circuit (PIC) that generatesmultiple wavelengths of the CW light, multiplexes the multiplewavelengths of CW light onto a common optical fiber or opticalwaveguide, and splits and amplifies the multiplexed optical power tomultiple output ports of the optical power supply 209 for transmissionto multiple corresponding CW light input ports of the TeraPHY chiplet107.

In various embodiments, the optical power supply 209 is opticallyconnected to the TeraPHY chiplet 107 through one or more opticalwaveguides 211. In various embodiments, the one or more opticalwaveguides 211 includes one or more optical fibers and/or one or moreoptical waveguide structures formed within the substrate 201. In someembodiments, the optical power supply 209 is attached to the substrate201. In some embodiments, the optical power supply 209 receiveselectrical power and electrical control signals through electricalconnections/routings formed within the substrate 201. In someembodiments, the optical power supply 209 is implemented as a devicephysically separate from the substrate 201. In some of theseembodiments, the optical power supply 209 is optically connected to theTeraPHY chiplet 107 through one or more optical fibers. In some of theseembodiments, the optical power supply 209 is optically connected to theTeraPHY chiplet 107 through one or more optical fibers that areoptically connected to the substrate 201 and through one or more opticalwaveguides formed within the substrate 201.

In some embodiments, the substrate 201 includes routings of electricaltraces configured to carry electrical power, electrical ground,electrical data input signals, and electrical data output signals forthe TeraPHY optical I/O chiplet 107 and the integrated circuit chip 205.In some embodiments, the integrated circuit chip 205 is electricallyconnected to the TeraPHY optical I/O chiplet 107 through the electricalconnections/routings 207 formed within the substrate 201. In someembodiments, the electrical connections/routings 207 are implementedwithin the substrate 201 as one or more RDL structure(s). FIG. 2B showsa vertical cross-section diagram of the substrate 201 of FIG. 2A, inaccordance with some embodiments. In some embodiments, the electricalconnections/routings 207 of the RDL structure(s) are formed in multiplelevels of the substrate 201. In some embodiments, the electricalconnections/routings 207 include electrically conductive via structuresformed to provide electrical connections between electrical tracesformed in different levels of the substrate 201, as represented by thevertical lines between different levels of the electricalconnections/routings 207 in FIG. 2B. It should be understood that invarious embodiments the electrical connections/routings 207 areconfigured in essentially any manner as needed to provide requiredelectrical connectivity between the integrated circuit chip 205 and theTeraPHY optical I/O chiplet 107, and to provide electrical power to eachof the integrated circuit chip 205 and the TeraPHY optical I/O chiplet107, and to provide a reference ground potential connection to each ofthe integrated circuit chip 205 and the TeraPHY optical I/O chiplet 107.

FIG. 2C shows interconnect metrics versus reach tradeoffs for variouselectrical and electro-optical semiconductor chip technologies,including the TeraPHY chiplets discussed herein, in accordance with someembodiments. More specifically, FIG. 2C shows where the TeraPHY chipletsdiscussed herein that implement wavelength division multiplexing (WDM)technology reside within a plot of a product of energy efficiency andbandwidth density versus maximum interconnect span (or datacommunication reach) for various interconnect technologies. The productof energy efficiency and bandwidth density is plotted in units ofGigabit per second per millimeter divided by picojoule per bit[(Gbps/mm)/(pJ/bit)]. The maximum interconnect span is plotted in unitsof meters (m). FIG. 2C shows that the TeraPHY chiplet WDM technology iscapable of providing communication over distances of a severalkilometers (km) at the bandwidth-density and energy-cost of in-packageinterconnects. FIG. 2C also shows various technology metrics andcomparison of the TeraPHY chiplet WDM technology with existingelectrical and optical technologies. In this manner, FIG. 2C shows anexample of where the TeraPHY chiplet WDM technology capability isparticularly relevant. FIG. 2C also shows that the TeraPHY chiplet WDMtechnology enables an off-package data communication reach of more thantwo km with power, bandwidth, and latency properties similar to anin-package electrical interconnect. The TeraPHY chiplet integrates tensof millions of transistors and hundreds of optical devices to providemultiple Tbps of I/O bandwidth off of a single semiconductor chiplet,e.g., complementary metal-oxide-semiconductor (CMOS) chip orsilicon-on-insulator (SOI) chip. Monolithic integration of transistorswith optical devices, such as microring resonators, enables seamlessinsertion of the TeraPHY chiplet into the CMOS/SOI multi-chip packagingecosystems, while at the same time enabling a flexible electricalinterface toward the host integrated circuit chip.

FIG. 3 shows an example organizational diagram of the TeraPHY chiplet107 referenced herein, in accordance with some embodiments. Theorganizational diagram has an electrical interface 301 separated (split)from a photonic interface 303. The photonic interface 303 is configuredto optically couple with a corresponding fiber array unit (FAU) 111 (seeFIG. 6B). In the example of FIG. 3, the electrical interface 301 is on aleft side of the TeraPHY chiplet 107, and the photonic interface 303(for the FAU 111) is on a right side of the TeraPHY chiplet 107. Anumber (1 to N) of optical macros 305-1 to 305-N are located between thephotonic interface 303 and the electrical interface 301. The electricalinterface 301 is connected to the optical macros 305-1 to 305-N by gluelogic 307. The electrical interface 301 of the TeraPHY chiplet 107 isadaptable to the logic of an integrated circuit chip to which theTeraPHY chiplet 107 connects. In the example of FIG. 3, the flow of datafrom electronics-to-optics is from left-to-right. Conversely, in theexample of FIG. 3, the flow of data from optics-to-electronics is fromright-to-left.

The electrical interface 301 is a block of circuitry configured tohandle all electrical I/O to and from the integrated circuit chip towhich the TeraPHY chiplet 107 connects, such as an Ethernet switchchip/die, or other type of integrated circuit chip. The optical macros305-1 to 305-N are responsible for conversion of data signals betweenthe optical and electrical domains. Specifically, each of the opticalmacros 305-1 to 305-N is configured to convert electrical data signalsreceived through the electrical interface 301 into optical data signalsfor transmission through the photonic interface 303. Also, each of theoptical macros 305-1 to 305-N is configured to convert optical datasignals received through the photonic interface 303 into electrical datasignals for transmission through the electrical interface 301. Thephotonic interface 303 is responsible for coupling optical signals toand from the optical macros 305-1 to 305-N. The glue logic 307 enablesflexible (dynamic or static) mapping of the electrical interface 301 tothe optical macros 305-1 to 305-N and associated optical wavelengths. Inthis manner, the glue logic 307 (also called crossbar circuitry)provides dynamic routing of electrical signals between the opticalmacros 305-1 to 305-N and the electrical interface 301. The glue logic307 also provides for retiming, rebuffering, and flit reorganizationfunctions at the phy-level. Also, in some embodiments, the glue logic307 implements various error correction and data-level link protocols tooffload some processing from the integrated circuit chip to which theTeraPHY chiplet 107 connects.

FIG. 4 shows an example layout of the TeraPHY chiplet 107, in accordancewith some embodiments. The layout of the optical and electricalcomponents of the TeraPHY chiplet 107 is designed to optimize areaefficiency, energy efficiency, performance, and practical considerationssuch as avoiding optical waveguide crossings. In some embodiments, theelectrical interface 301 is laid out along one chip edge (left side edgein FIG. 4), and the photonic interface 303 for optical coupling with theFAU 111 is laid out along the opposite chip edge (right side edge inFIG. 4). In some embodiments, the photonic interface 303 includes anoptical grating coupler for each of the optical fibers in the FAU 111.In various embodiments, the photonic interface 303 includes verticaloptical grating couplers, edge optical couplers, or essentially anyother type of optical coupling device, or combination thereof to enableoptical coupling of the FAU 111 with the optical macros 305-1 to 305-N.In some embodiments, the photonic interface 303 is configured tointerface with 24 optical fibers within the FAU 111. In someembodiments, the photonic interface 303 is configured to interface with16 optical fibers within the FAU 111.

The glue logic 307 routes data between the electrical interface 301 andthe optical macros 305-1 to 305-N. The glue logic 307 includes cross-barswitches and other circuitry as needed to interface the electricalinterface 301 connections with the optical macros 305-1 to 305-N. Insome embodiments, the optical transmitters (Tx) and optical receivers(Rx) of the optical macros 305-1 to 305-N are combined in pairs, witheach Tx/Rx pair forming an optical transceiver. The glue logic 307enables dynamic mapping of electrical lanes/channels to opticallanes/channels. The optical macros 305-1 to 305-N (for data transmitting(Tx) and data receiving (Rx)) are laid out in between the glue logic 307and the photonic interface 303 that couples with the FAU 111. Theoptical macros 305-1 to 305-N include both optical and electricalcircuitry responsible for converting electrical signals to opticalsignals and for converting optical signals to electrical signals.

In some embodiments, the electrical interface 301 is configured toimplement the Advanced Interface Bus (AIB) protocol to enable electricalinterface between the TeraPHY chiplet 107 and one or more otherintegrated circuit chips. It should be understood, however, that inother embodiments the electrical interface 107 can be configured toimplement essentially any electrical data communication interface otherthan AIB. For example, in some embodiments, the electrical interface 107includes a High Bandwidth Memory (HBM) and Kandou Bus forserialization/deserialization of data.

In some embodiments, the TeraPHY chiplet 107 has a length d1 and a widthd2, where d1 is about 8.9 millimeters (mm) and d2 is about 5.5 mm. Itshould be understood that the term “about,” as used herein, means +/−10%of a given value. In some embodiments, the length d1 is less than about8.9 mm. In some embodiments, the length d1 is greater than about 8.9 mm.In some embodiments, the width d2 is less than about 5.5 mm. In someembodiments, the width d2 is greater than about 5.5 mm. In someembodiments, the electrical interface 301 has a width d3 of about 1.3mm. In some embodiments, the width d3 is less than about 1.3 mm. In someembodiments, the width d3 is greater than about 1.3 mm. In someembodiments, the photonic interface 303 for the optical fiber array hasa length d4 of about 5.2 mm and a width d5 of about 2.3 mm. In someembodiments, the length d4 is less than about 5.2 mm. In someembodiments, the length d4 is greater than about 5.2 mm. In someembodiments, the optical macros 305-1 to 305-N have a width d6 of about1.8 mm. In some embodiments, the width d6 is less than about 1.8 mm. Insome embodiments, the width d6 is greater than about 1.8 mm. In someembodiments, each transmitter Tx and receiver Rx optical macro 305-1 to305-N pair has a length d7 of about 0.75 mm. In some embodiments, thelength d7 is less than about 0.75 mm In some embodiments, the length d7is greater than about 0.75 mm. In some embodiments, the transmitter Txand receiver Rx optical macros 305-1 to 305-N are positioned to alignwith an optical fiber pitch within the photonic interface 303. In someembodiments, the length d7 of each optical macro 305-1 to 305-N (pair oftransmitter (Tx) and receiver (Rx) optical macros) is matched to thepitch of the optical fibers in a standard optical fiber ribbon. Forexample, if the optical fiber pitch is 250 micrometers, and three of theoptical fibers in the optical fiber ribbon correspond to one opticalmacro 305-1 to 305-N (one optical fiber brings continuous wave light tothe transmitter (Tx) optical macro from a laser, one optical fibertransmits data as modulated light from the transmitter (Tx) opticalmacro, and one optical fiber brings modulated light carrying encodeddata to the receiver (Rx) optical macro), then the optical macro lengthd7 is 750 micrometers.

In some embodiments, the number N of optical macros 305-1 to 305-N is 8.In some embodiments, the number N of optical macros 305-1 to 305-N isless than 8. In some embodiments, the number N of optical macros 305-1to 305-N is greater than 8. Also, each of the optical macros 305-1 to305-M represents at least one optical port. In some embodiments, a dualphase lock loop (PLL) circuit is shared by each transmitter Tx/receiverRx pair within the optical macros 305-1 to 305-N. In some embodiments,the dual PLL includes a PLLU that covers a frequency range from 24GigaHertz (GHz) to 32 GHz, and a PLLD that covers a frequency range from15 GHz to 24 GHz.

The TeraPHY chiplet 107 also includes management circuits 401 andgeneral purpose input/output (GPIO) components 403 for communicatingelectrical data signals to and from the TeraPHY chiplet 107. In variousembodiments, the GPIO components 403 include Serial Peripheral Interface(SPI) components and/or another type of component to enable off-chipdata communication. Also, in some embodiments, the TeraPHY chiplet 107includes many other circuits, such as memory (e.g., SRAM), a CPU, analogcircuits, and/or any other circuit that is implementable in CMOS.

In some embodiments, the TeraPHY optical I/O chiplet 107 has a coarsewavelength division multiplexing 4-lane (CWDM4) configuration in whicheach of the optical macros 305-1 to 305-N includes fourserializer/deserializer (SerDes) slices (FR-4) or eight SerDes slices(FR-8). In some embodiments, the optical macros 305-1 to 305-N aredivided into wavelength transmit (Tx)/receive (Rx) slices, with eachTx/Rx slice including fully integrated analog Tx/Rx front-ends,serialization/deserialization, clock-data-recovery, and microringresonator thermal tuning digital control. In some embodiments, thephotonic components integrated in each Tx/Rx slice/optical macro 305-xoptical port are based on microring resonators (such as modulators,filters, etc.). In some embodiments, the TeraPHY optical I/O chiplet 107optically couples to the FAU 111 through edge-coupled V-groovestructures with embedded mode-converters.

FIG. 5A shows a top view of a semiconductor wafer 501 on which manyTeraPHY optical I/O chiplets 107 are fabricated, in accordance with someembodiments. FIG. 5A also shows a close-up view 503 of a substrate sideof a given TeraPHY optical I/O chiplet 107 singulated from the wafer501, after removal of a substrate thickness from the given TeraPHYoptical I/O chiplet 107. FIG. 5A also shows the electrical interface 301(AIB Interface), the glue logic 307 (Crossbar), the optical macros 305-1to 305-N (TeraPHY ports), and the photonic interface 303 (FiberCouplers) of the given TeraPHY optical I/O chiplet 107. FIG. 5A alsoshows a close-up view 505 of the electrical connection side of the givenTeraPHY optical I/O chiplet 107 that includes a parallel interfacesection 507 and a parallel electrical interface bump pitch patternsection 509 used to electrically connect the given TeraPHY optical I/Ochiplet 301 to electrical connections/routings 207 in the substrate 201,as discussed with regard to FIG. 2A. In various embodiments, the TeraPHYoptical I/O chiplet 107 is electrically connected to the integratedcircuit chip 205 with low-power, short reach in-package electricalinterconnect technologies, such as through a redistribution layer (RDL)structure formed within the substrate 201.

FIG. 5B shows a scanning electron microscope (SEM) image 511 of aportion of the electrical connection bumps 507A in the parallelinterface section 507 and a portion of the electrical connection bumps509A in the parallel electrical interface bump pitch pattern section 509of the TeraPHY optical I/O chiplet 107, in accordance with someembodiments. In some embodiments, the electrical connection bumps 507Aare arranged in accordance with a bump pitch (bump center-to-bump centerdistance) of about 55 micrometers. However, it should be understood thatin various embodiments, the electrical connection bumps 507A arearranged in accordance with a pitch that is either less than or greaterthan about 55 micrometers.

FIG. 6A shows an example layout of photonic structures of the TeraPHYoptical I/O chiplet 107, in accordance with some embodiments. FIG. 6Ashows some optical waveguides 601 and associated optical gratingstructures 603 of the optical layout of the TeraPHY optical I/O chiplet107, but some portions of the electro-optical layout such as opticalmicroring resonators and associated electronics are not shown in orderto avoid obscuring the optical layout of FIG. 6A. The floorplan of theTeraPHY optical I/O chiplet 107 has the optical fibers coming in on theright side of the TeraPHY optical I/O chiplet 107. Light is coupled fromthe optical fibers into the optical grating couplers 603 on the TeraPHYoptical I/O chiplet 107. The light coupled into the optical gratingcouplers 603 is guided by the optical waveguides 601 to the inputs ofthe optical macros 305-1 to 305-N. In some embodiments, each opticalmacro 305-1 to 305-N has three optical fiber connections, including oneoptical fiber connection for the continuous wave laser light input tothe optical transmitter (Tx input), one optical fiber connection for theoptical output from the optical transmitter (Tx output), and one opticalfiber connection for the modulated optical input to the optical receiver(Rx input).

In some embodiments, the optical layout shown in FIG. 6A usessingle-polarization optical grating couplers 603 as the optical couplingstructures from the optical fibers to the TeraPHY optical I/O chiplet107. In some embodiments, when the TeraPHY optical I/O chiplet 107 usesdual-polarization inputs, the optical layout includes polarizationsplitting optical grating couplers 603 followed by an optical combinerstructure. In some embodiments, when the TeraPHY optical I/O chiplet 107uses dual-polarization inputs and the optical grating couplers 603support both TE/TM polarization states, the optical layout includes apolarization splitter-rotator followed by an optical combiner structure,such that the optical waveguide interfaces (Tx input, Tx output, Rxinput) to the optical macros 305-1 to 305-N have a single polarization.In various embodiments, the optical layout of FIG. 6A is mirrored,rotated, or both mirrored and rotated. Also, in some embodiments, theoptical fiber coupler array 303 organization of the TeraPHY optical I/Ochiplet 107 includes optical edge couplers based on mode converters,V-grooves, and/or other optical fiber coupling mechanisms.

FIG. 6B shows the example FAU 111 for connection to the TeraPHY opticalI/O chiplet 107, in accordance with some embodiments. In someembodiments, the FAU 111 connects multiple optical fibers to the TeraPHYoptical I/O chiplet 107. In some embodiments, the FAU 111 includes anoptical fiber pigtail 607 that includes multiple optical fibers thatconnect to the optical fiber coupler array 303 of the TeraPHY opticalI/O chiplet 107. In some embodiments, some of the optical fibers withinthe optical fiber pigtail 607 are polarization maintaining single modeoptical fibers (PMF), such as used for carrying continuous wave laserlight from an external laser device to the TeraPHY chiplet 107. Also, insome embodiments, some of the optical fibers within the optical fiberpigtail 607 are non-polarization maintaining single mode optical fibers(SMF) for carrying modulated light signals to and/or from the TeraPHYoptical I/O chiplet 107. In some embodiments, the FAU 111 includes amechanical transfer (MT) ferrule 609, such as an MTP® connector, orother similar type of optical connector. In some embodiments, the FAU111 is configured to connect up to 24 optical fibers to the TeraPHYoptical I/O chiplet 107. For example, in some embodiments, the MTferrule 609 is configured as a 2×12 MTP® connector ferrule, or othersimilar type of optical connector.

FIG. 6C shows a close-up layout view of a set of optical gratingcouplers 611, 613, 615 for a given optical macro 305-x of the opticalmacros 305-1 to 305-N, corresponding to an optical port region 605 asshown in FIG. 6A, in accordance with some embodiments. Each opticalgrating coupler 611, 613, 615 is optically coupled to a correspondingoptical fiber. In some embodiments, the optical grating coupler 611 isoptically coupled to the corresponding optical fiber through whichcontinuous wave laser light is supplied to the optical macro 305-x. Inthese embodiments, the optical grating coupler 611 is also opticallycoupled to an optical waveguide 617 that supplies the continuous wavelaser light to the optical macro 305-x. Also, in these some embodiments,the optical grating coupler 613 is optically coupled to an opticalwaveguide 619 through which modulated light signals are output from theoptical macro 305-x. Also, in these embodiments, the optical gratingcoupler 613 is also optically coupled to the corresponding optical fiberthrough which the modulated light signals are transmitted.

In some embodiments, the optical grating coupler 613 is opticallycoupled to the corresponding optical fiber through which continuous wavelaser light is supplied to the optical macro 305-x. In theseembodiments, the optical grating coupler 613 is also optically coupledto the optical waveguide 619 that supplies the continuous wave laserlight to the optical macro 305-x. Also, in these embodiments, theoptical grating coupler 611 is optically coupled to the opticalwaveguide 617 through which modulated light signals are output from theoptical macro 305-x. Also, in these embodiments, the optical gratingcoupler 611 is also optically coupled to the corresponding optical fiberthrough which the modulated light signals are transmitted.

The optical grating coupler 615 is optically coupled to an optical fiberthrough which modulated light signals are received by the TeraPHYoptical I/O chiplet 107. The optical grating coupler 615 is alsooptically coupled to an optical waveguide 621 that supplies the receivedmodulated light signals to the optical macro 305-x. The opticalwaveguides 617, 619, and 621 are formed within the TeraPHY optical I/Ochiplet 107 to route/guide light between the optical grating couplers611, 613, and 615, respectively, and the optical macro 305-x. In someembodiments, optical alignment structures 623, 625, and 627 are formedaround the optical grating couplers 611, 613, and 615, respectively, toassist with alignment of the corresponding optical fibers to the opticalgrating couplers 611, 613, and 615.

FIG. 6D shows a close-up view of the optical grating coupler 615corresponding to a region 629 as shown in FIG. 6C, in accordance withsome embodiments. The optical grating coupler 615 is configured as avertical optical grating coupler to which an optical fiber is opticallycoupled. The optical grating coupler 615 is optically coupled to theoptical waveguide 621 that routes light directly to the optical macro305-x. In the example embodiment of FIG. 6D, the optical grating coupler615 is also optically coupled to an optical waveguide 631 that initiallyroutes light in a direction away from the optical macro 305-x and thenroutes the light around 180 degrees back towards the optical macro305-x. In various embodiments, the optical waveguide 631 is implementedand used as needed based on whichever initial light propagationdirection away from the optical grating coupler 615 is more efficient atcoupling light between the corresponding optical fiber and the opticalwaveguide 621 that optically connects to the optical macro 305-x. Itshould be understood that in some embodiments the optical gratingcouplers 611 and 613 are formed in a similar manner as the opticalgrating coupler 615 so as to also optically connect to a loop-backoptical waveguide that initially extends from the optical gratingcoupler in a direction away from the optical macro 305-x and thatsubsequently turns back toward the optical macro 305-x. For example,with reference to FIG. 6C, in some embodiments, the optical gratingcoupler 611 also optically connects to a loop-back optical waveguide633, and the optical grating coupler 613 also optically connects to aloop-back optical waveguide 635. Additionally, in some embodiments, oneor more of the vertical optical grating couplers 611, 613, and 615 isreplaced by a corresponding horizontal optical grating coupler to enableedge-coupling of corresponding optical fiber to the TeraPHY optical I/Ochiplet 107.

FIG. 7 shows an example layout of a given one of the optical macros305-1 to 305-N, referred to as optical macro 305-x, in accordance withsome embodiments. The optical macro 305-x includes a number M oftransmit (Tx) slices 701-1 to 701-M and a number M of receive (Rx)slices 703-1 to 703-M. An optical slice of the optical macro 305-xrefers to either a single one of the optical transmitter slices 701-1 to701-M, or a single one of the optical receiver slices 703-1 to 703-M, ora combination of a single one of the optical transmitter slices 701-1 to701-M and a corresponding single one of the optical receiver slices703-1 to 703-M, where the single one of the optical transmitter slices701-1 to 701-M and the single one of the optical receiver slices 703-1to 703-M are controlled to operate on a single wavelength of light. Theexample layout of FIG. 7 shows the routing of an optical waveguide 705and the placement of optical microring resonators 707-1 to 707-M withinthe transmit (Tx) portion of the optical macro 705-x. The microringresonators 707-1 to 707-M function as modulators. The example layout ofFIG. 7 also shows the routing of an optical waveguide 709 and theplacement of optical microring resonators 711-1 to 711-M within thereceive (Rx) portion of the optical macro 705-x. The microringresonators 711-1 to 711-M function as photodetectors. In someembodiments, one or more of the microring resonators 707-1 to 707-M and711-1 to 711-M are controlled to function as an optical multiplexerand/or as an optical demultiplexer.

Each corresponding pair of the transmit (Tx) slices 701-1 to 701-M andthe receive (Rx) slices 703-1 to 703-M forms a Tx/Rx slice of theoptical macro 305-x. For example, Tx Slice 1 701-1 and Rx Slice 1 703-1together form a Slice 1 of the optical macro 305-x. The transmit (Tx)slices 701-1 to 701-M include electrical circuitry for directingtranslation of electrical data in the form of a bit stream into a streamof modulated light by operating the microring resonators 707-1 to 707-Mto modulate the continuous wave laser light at a given wavelengthincoming through the optical waveguide 617 from the optical gratingcoupler 611 into a stream of modulated light at the given wavelength,with the stream of modulated light at the given wavelength beingtransmitted from the optical macro 305-x through the optical waveguide619 to the optical grating coupler 613. In some embodiments, each of thetransmit (Tx) slices 701-1 to 701-M includes electrical circuitry forinphase signal generation and/or quadrature signal generation, injectionlocked oscillator circuitry, and phase interpolator circuitry. Thereceive (Rx) slices 703-1 to 703-M include electrical circuitry fordetecting light of a given wavelength within a stream of modulated lightincoming through the optical waveguide 621 from the optical gratingcoupler 615 by operating the microring resonators 711-1 to 711-M. Theelectrical circuity within the receive (Rx) slices 703-1 to 703-Mtranslate the light that is detected by the microring resonators 711-1to 711-M at a corresponding wavelength into a bit stream in theelectrical domain. In some embodiments, each of the receive (Rx) slices703-1 to 703-M includes electrical circuitry for inphase signalgeneration and/or quadrature signal generation (I/Q signal generation),injection locked oscillator (ILO) circuitry, phase interpolator (PI)circuitry, transimpedance amplifier (TIA) circuitry, and signalequalization (EQ) circuitry. In some embodiments, the receive (Rx)slices 703-1 to 703-M utilize a respective dummy microring photodetector(PD) for better matching in the receiver analog front-end and forrobustness to common-mode noise (e.g., supply).

The optical waveguide 617 routes continuous wave laser light from theoptical grating coupler 611 to each of the microring resonators 707-1 to1507-M within the transmit (Tx) slices 701-1 to 701-M. The opticalwaveguide 619 also routes modulated light from the microring resonators707-1 to 707-M within the transmit (Tx) slices 701-1 to 701-M to theoptical grating coupler 613 for transmission out of the TeraPHY opticalI/O chiplet 107. In some embodiments, the optical waveguide 617 and theoptical waveguide 619 are parts of a single, continuously formed opticalwaveguide. In some embodiments, each of the microring resonators 707-1to 707-M within the transmit (Tx) slices 701-1 to 701-M is tunable tooperate at a specified wavelength of light. Also, in some embodiments,the specified wavelength of light at which a given microring resonator707-x is tuned to operate is different than the specified wavelengths atwhich the other microring resonators 707-1 to 707-M, excluding 707-x,are tuned to operate. In some embodiments, a corresponding heatingdevice 708-1 to 708-M is positioned near each of the microringresonators 707-1 to 707-M to provide for thermal tuning of the resonantwavelength of the microring resonator. In some embodiments, acorresponding heating device 708-1 to 708-M is positioned within aninner region circumscribed by a given microring resonator 707-x toprovide for thermal tuning of the resonant wavelength of the givenmicroring resonator 707-x. In some embodiments, the heating device 708-1to 708-M of each of the microring resonators 707-1 to 707-M is connectedto corresponding electrical control circuitry within the correspondingtransmit (Tx) slice that is operated to thermally tune the resonantwavelength of the microring resonator. In some embodiments, each of themicroring resonators 707-1 to 707-M is connected to correspondingelectrical tuning circuitry within the corresponding transmit (Tx) slicethat is operated to electrically tune the resonant wavelength of themicroring resonator. In various embodiments, each of the microringresonators 707-1 to 707-M operates as part of an optical modulatorand/or optical multiplexer.

The optical waveguide 621 routes incoming modulated light from theoptical grating coupler 615 to the microring resonators 711-1 to 711-Mwithin the receive (Rx) slices 703-1 to 703-M. In some embodiments, eachof the microring resonators 711-1 to 711-M within the receive (Rx)slices 703-1 to 703-M is tunable to operate at a specified wavelength oflight. Also, in some embodiments, the specified wavelength of light atwhich a given microring resonator 711-x is tuned to operate is differentthan the specified wavelengths at which the other microring resonators711-1 to 711-M, excluding 711-x, are tuned to operate. In someembodiments, a corresponding heating device 712-1 to 712-M is positionednear each of the microring resonators 711-1 to 711-M to provide forthermal tuning of the resonant wavelength of the microring resonator. Insome embodiments, a corresponding heating device 712-1 to 712-M ispositioned within an inner region circumscribed by a given microringresonator 711-x to provide for thermal tuning of the resonant wavelengthof the given microring resonator 711-x. In some embodiments, the heatingdevice 712-1 to 712-M of each of the microring resonators 711-1 to 711-Mis connected to corresponding electrical control circuitry within thecorresponding receive (Rx) slice that is operated to thermally tune theresonant wavelength of the microring resonator. In some embodiments,each of the microring resonators 711-1 to 711-M is connected tocorresponding electrical tuning circuitry within the correspondingreceive (Rx) slice that is operated to electrically tune the resonantwavelength of the microring resonator. In various embodiments, each ofthe microring resonators 711-1 to 711-M operates as part of aphotodetector and/or optical demultiplexer.

In some embodiments, the architecture and floorplan of the optical macro305-x is variable by including a different number of PLLs at variouspositions within the optical macro 305-x. For example, in someembodiments, a centralized PLL is positioned within the clock spine andfans out to the slices at both sides of the optical macro 305-x. Invarious embodiments, the PLL is replicated as multiple PLL instancesacross the optical macro 305-x, with each PLL instance either dedicatedto a given transmit (Tx)/receive (Rx) slice or shared with a subset oftransmit (Tx)/receive (Rx) slices. In various embodiments, otherfloorplan configurations of the optical macro 305-x include multiplecolumns of optical macros with pass-through photonic rows, to increasethe edge bandwidth density, and/or staggering of the transmit (Tx) andreceive (Rx) optical macros side-by-side to increase the edge bandwidthdensity.

The optical macro 305-x includes both photonic and electroniccomponents. The optical waveguides 617, 619, and 621 are laid out in theoptical macro 305-x so as to avoid optical waveguide crossings and so asto minimize optical waveguide length, which minimizes optical losses,and correspondingly improves the energy efficiency of the system. Theoptical macro 305-x is laid out in such a way as to minimize thedistance between the electronic components and the optical components inorder to minimize electrical trace length, which improves the energyefficiency of the optical macro 305-x, enables faster signaltransmission, and reduces chip size.

The TeraPHY optical I/O chiplet 107 includes the set of (N) opticalmacros 305-1 to 305-N. Each optical macro 305-x includes the set of (M)optical transmitter slices 701-1 to 701-M and optical receiver slices703-1 to 703-M that are logically grouped together to transmit orreceive bits on a number (W) of different optical wavelengths on therespective optical waveguide 617/619 and 621. In various embodiments,the number (M) of optical transmitter slices 701-1 to 701-M and opticalreceiver slices 703-1 to 703-M and the number (W) of different opticalwavelengths can be defined as needed, considering that any number ofoptical transmitter slices 701-1 to 701-M and/or optical receiver slices703-1 to 703-M is tunable to a given one of the number (W) of opticalwavelengths. However, if data bits are being transmitted or received bymultiple ones of the optical microring resonators 707-1 to 707-M, or bymultiple ones of the optical microring resonators 711-1 to 711-M, tunedto the same optical wavelength, channel/wavelength contention ismanaged. The floorplan and organization of the optical macro 305-xrepresent adjustable degrees of freedom for controlling the followingmetrics:

-   -   length of optical waveguides 617, 619, 621 (which directly        correlates with optical loss)    -   optical macro 305-x area (which correlates with manufacturing        cost)    -   energy consumed per bit (energy efficiency)    -   electrical signaling integrity (which correlates with        performance)    -   electrical package escape (the amount of electrical data input        and output that is physically available for a given set of chip        dimensions and for a given spacing/pitch of electrical bumps)    -   optical package escape (the amount of optical data input and        output that is physically available for a given set of chip        dimensions and for a given spacing/pitch of optical fibers).

FIG. 8A shows a diagram of a first computer system 801 opticallyconnected to a second computer system 803 through an optical link 805,in accordance with some embodiments. In various embodiments, the firstcomputer system 801 represents essentially any packaged set ofsemiconductor chips that includes at least one integrated circuit chip205A electrically connected to at least one TeraPHY optical I/O chiplet107A, as indicated by electrical connections/routings 207A. In someembodiments, the at least one integrated circuit chip 205A and the atleast one TeraPHY optical I/O chiplet 107A are packaged on a commonsubstrate 201A. The at least one TeraPHY optical I/O chiplet 107A isconnected to receive optical power from an optical power supply 209Athrough one or more optical waveguides 211A. The at least one TeraPHYoptical I/O chiplet 107A corresponds to the TeraPHY chiplet 107discussed herein. The optical power supply 209A is that same as theoptical power supply 209 described with regard to FIG. 2A.

In various embodiments, the second computer system 803 representsessentially any packaged set of semiconductor chips that includes atleast one integrated circuit chip 205B electrically connected to atleast one TeraPHY optical I/O chiplet 107B, as indicated by electricalconnections/routings 207B. In some embodiments, the at least oneintegrated circuit chip 205B and the at least one TeraPHY optical I/Ochiplet 107B are packaged on a common substrate 201B. The at least oneTeraPHY optical I/O chiplet 107B is connected to receive optical powerfrom an optical power supply 209B through one or more optical waveguides211B. The at least one TeraPHY optical I/O chiplet 107B corresponds tothe TeraPHY chiplet 107 discussed herein. The optical power supply 209Bis that same as the optical power supply 209 described with regard toFIG. 2A. Also, in some embodiments, the optical power supplies 209A and209B are the same optical power supply. The TeraPHY optical I/O chiplet107A of the first computer system 801 is optically connected to theTeraPHY optical I/O chiplet 107B of the second computer system 803through the optical link 805. In some embodiments, the optical link 805is an optical fiber array.

FIG. 8B shows a more detailed view of the optical connections betweenthe TeraPHY optical I/O chiplet 107A of the first computer system 801and the TeraPHY optical I/O chiplet 107B of the second computer system803, in accordance with some embodiments. In some embodiments, each ofthe TeraPHY optical I/O chiplets 107A and 107B is configured in the samemanner as TeraPHY optical I/O chiplet 107 described herein. The TeraPHYoptical I/O chiplet 107A includes at least one optical macro 305A. TheTeraPHY optical I/O chiplet 107B includes at least one optical macro305B. Each of the optical macros 305A and 305B is configured in the samemanner as the optical macro 305-x described herein.

The optical grating coupler 613 of the optical macro 305A is opticallyconnected to the optical power supply 209A through one or more opticalwaveguides 211A, e.g., optical fibers. The optical grating coupler 611of the optical macro 305A is optically connected to the optical gratingcoupler 615 of the optical macro 305B. In this manner, modulated opticalsignals generated by the transmitter slices 701-1 through 701-M of theoptical macro 305A are transmitted to the receiver slices 703-1 through703-M of the optical macro 305B. In some embodiments, the modulatedoptical signals generated by the transmitter slices 701-1 through 701-Mconvey data received by the optical macro 305A from the integratedcircuit chip 205A in the form of electrical signals. The modulatedoptical signals that convey the data are optically coupled into theoptical microring resonators 711-1 through 711-M of the optical macro305B and are de-modulated by the receiver slices 703-1 through 703-M ofthe optical macro 305B into electrical signals that are transmitted tothe integrated circuit chip 205B through the electricalconnections/routings 207B.

The optical grating coupler 613 of the optical macro 305B is opticallyconnected to the optical power supply 209B through one or more opticalwaveguides 211B, e.g., optical fibers. The optical grating coupler 611of the optical macro 305B is optically connected to the optical gratingcoupler 615 of the optical macro 305A. In this manner, modulated opticalsignals generated by the transmitter slices 701-1 through 701-M of theoptical macro 305B are transmitted to the receiver slices 703-1 through703-M of the optical macro 305A. In some embodiments, the modulatedoptical signals generated by the transmitter slices 701-1 through 701-Mof the optical macro 305B convey data provided by the integrated circuitchip 205B through the electrical connections/routings 207B to theoptical macro 305B. The modulated optical signals that convey the dataprovided by the integrated circuit chip 205B are optically coupled intothe optical microring resonators 711-1 through 711-M of the opticalmacro 305A and are de-modulated by the receiver slices 703-1 through703-M of the optical macro 305A into electrical signals that aretransmitted to chip 205A through the electrical connections/routings207A.

The TeraPHY optical I/O chiplet 107 has a small footprint because theintellectual property (IP) building blocks on the chiplet are dense.These IP building blocks include the optical microring resonators, whichare used for multiplexing and demultiplexing multiple wavelengths oflight onto optical waveguides, as well as modulating light andfunctioning as photodetectors, in a very small chip area (for example 10micrometer diameter per microring resonator). The IP building blocks onthe chip are also dense because the electrical circuitry that controlsthe optical devices is closely integrated on the same chip with theoptical devices that they control, making it possible to optimize spaceefficiency.

In various embodiments, the optical macros 305-1 to 305-N within theTeraPHY optical I/O chiplet 107 can be configured in different ways withregard to optical path layouts (placement, orientation, shape, size,etc., of optical waveguides and microring resonators), routingfloorplans (electrical signal routing and/or optical signal routing),and organization of electronic-photonic components and circuitry (e.g.,transmit (Tx) slices 701-1 to 701-M, receive (Rx) slices 703-1 to 703-M,clock spline circuitry, electrical interface glue circuitry,phase-lock-loop circuitry, etc.). FIGS. 9 through 16 show variousexample optical macro 305-1 to 305-N configuration embodiments withinthe TeraPHY optical I/O chiplet 107 with regard to optical path layouts,routing floorplans, and organization of electronic-photonic componentsand circuitry. For deeply-scaled planar electrical fabricationprocesses, such as, but not limited to, 45 nanometer (nm) fabricationtechnology node processes, the orientation (the long edge) of thetransistor gate electrode layer is fixed across the wafer. In someembodiments, the example optical macro 305-1 to 305-N configurationsdescribed with regard to FIGS. 9 through 16 assume that the waferorientation is set such that the longer edges of the gate electrodestructures within the gate electrode layer extend in a North-Southdirection. While FIGS. 9 through 16 show some example optical macro305-1 to 305-N configuration embodiments for implementation within theTeraPHY optical I/O chiplet 107, it should be understood that variouspermutations of these optical macro 305-1 to 305-N configurationembodiments are possible and valid. For example, any of the exampleoptical macro 305-1 to 305-N configuration embodiments of FIGS. 9through 16 can be rotated to essentially any angle (relative to theNorth-South direction across the wafer) and/or implemented in a mirroredconfiguration (North-South and/or East-West) from what is shown in FIGS.9 through 16. Also, in various embodiments, any of the example opticalmacro 305-1 to 305-N configuration embodiments of FIGS. 9 through 16 canbe modified with regard to lengths of optical waveguide segments,curvatures of optical waveguide segments, relative positioning betweenmicroring resonators and optical waveguides, relative positioningbetween microring resonators along a given optical waveguide, number ofmicroring resonators along a given optical waveguide, relativepositioning between electronic control circuitry and correspondingmicroring resonators, among other parameters.

In various embodiments, the gate electrode layer of the TeraPHY opticalI/O chiplet 107 (and of the wafer in general) includes gate electrodestructures formed of polysilicon, metal, and/or essentially any othermaterial that can be used as the gate electrode of a field effecttransistor (e.g., metal-oxide-semiconductor field effect transistor(MOSFET) or junction field effect transistor (JFET)), bipolar junctiontransistor (BJT), and/or other type of transistor device. It should beunderstood that the various optical macro 305-1 to 305-N configurationembodiments described herein, such as with regard to FIGS. 7 and 9through 16, can be fabricated using essentially any semiconductormanufacturing process, and are particularly well-suited for fabricationusing CMOS semiconductor manufacturing processes. Also, the variousoptical macro 305-1 to 305-N configuration embodiments described hereincan be implemented independent of whether the transistors formed withinthe TeraPHY optical I/O chiplet 107 are planar transistors, FinFETtransistors, nanowire-FET transistors, silicon-on-insulator transistors,and/or any other type of transistor. Also, the various optical macro305-1 to 305-N configuration embodiments described herein can beimplemented with the photonic components (optical waveguides, microringresonators, etc.) formed in the body silicon of the TeraPHY optical I/Ochiplet 107, deposited as polysilicon structures within the TeraPHYoptical I/O chiplet 107, and/or formed as structures in anotheroptically enabled layer of the TeraPHY optical I/O chiplet 107.

The various example optical macro 305-x configuration embodiments ofFIGS. 7 and 9 through 16 show the routing of optical waveguides,relative locations of optical microring resonators, and relativelocations of circuits/electronics. It should be understood that invarious embodiments the optical microrings shown in the example opticalmacro 305-x configurations of FIGS. 9 through 16 can be controlled tooperate as optical modulators, optical multiplexers, opticalphotodetectors, optical demultiplexers, optical add/drop filters, and/oras any other optical component that is implementable as an opticalmicroring resonator. The various optical macro 305-x configurationembodiments of FIGS. 7 and 9 through 16 show examples of various opticalpath layouts (optical waveguide paths) and microring resonatororganizations that: 1) optimize the interconnect parasitics betweendriver/receiver electronic circuits and photonic components, 2) optimizethe global macro clock distribution, and 3) optimize the time-of-flightpath length mismatch between the optical macro 305-x coupling points andreceiver photodetectors.

FIG. 9 shows an example optical path layout of an optical macro 305-x 1for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a U-shaped optical waveguide 901, inaccordance with some embodiments. The optical waveguide 901 includes afirst horizontal (East-West oriented) segment 901A, a curved segment901B, and a second horizontal (East-West oriented) segment 901C. In someembodiments, the curved segment 901B curves around about 180 degreesfrom the first horizontal segment 901A to the second horizontal segment901C, vice-versa. The first horizontal segment 901A is opticallyconnected to a first optical port 902A, and the second horizontalsegment 901B is optically connected to a second optical port 902B. Invarious embodiments, the first optical port 902A is formed as a verticaloptical grating coupler or a horizontal (edge) optical grating coupler.Also, in various embodiments, the second optical port 902B is formed asa vertical optical grating coupler or a horizontal (edge) opticalgrating coupler.

In some embodiments, the first horizontal segment 901A, the curvedsegment 901B, and the second horizontal segment 901C of the opticalwaveguide 901 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 901A, the curved segment 901B, and the secondhorizontal segment 901C of the optical waveguide 901 is/are formed of adifferent material than one or more others of the first horizontalsegment 901A, the curved segment 901B, and the second horizontal segment901C of the optical waveguide 901, such that the optical waveguide 901is formed as a combination of materials, e.g., a combination of two ormore of silicon, polysilicon, silicon nitride, and/or any other materialsuitable for use as an optical waveguide. Also, in some embodiments,each of the first horizontal segment 901A, the curved segment 901B, andthe second horizontal segment 901C of the optical waveguide 901 isformed to have a substantially similar vertical cross-section shape.However, in some embodiments, any one or more of the first horizontalsegment 901A, the curved segment 901B, and the second horizontal segment901C of the optical waveguide 901 is/are formed to have a differentvertical cross-section shape than one or more others of the firsthorizontal segment 901A, the curved segment 901B, and the secondhorizontal segment 901C of the optical waveguide 901. Also, in someembodiments, any one or more of the first horizontal segment 901A, thecurved segment 901B, and the second horizontal segment 901C of theoptical waveguide 901 is/are formed to have a vertical cross-sectionshape that varies along its length in the direction of light propagationthrough the optical waveguide 901.

The optical macro 305-x 1 includes optical microring resonators 903-1 to903-X (where X is an integer greater than zero) that are opticallycoupled to the first horizontal segment 901A of the U-shaped opticalwaveguide 901, such that light traveling through the optical waveguide901 can be evanescently coupled into the optical microring resonators903-1 to 903-X, and such that light traveling through the opticalmicroring resonators 903-1 to 903-X can be evanescently coupled into theoptical waveguide 901. The optical macro 305-x 1 also includes opticalmicroring resonators 905-1 to 905-Y (where Y is an integer greater thanzero) that are optically coupled to the second horizontal segment 901Cof the U-shaped optical waveguide 901, such that light traveling throughthe optical waveguide 901 can be evanescently coupled into the opticalmicroring resonators 905-1 to 905-Y, and such that light travelingthrough the optical microring resonators 905-1 to 905-Y can beevanescently coupled into the optical waveguide 901. The optical macro305-x 1 shows a particular example of an optical layout in which each ofthe optical microring resonators 903-1 to 903-X and 905-1 to 905-Y isoptically coupled to one of the two horizontal segments 901A and 901C ofthe U-shaped optical waveguide 901. Also, in the optical layout of theoptical macro 305-x 1, each of the optical microring resonators 903-1 to903-X and 905-1 to 905-Y is positioned along an outer side/edge of theU-shaped optical waveguide 901. In some embodiments, the opticalmicroring resonators 903-1 to 903-X and 905-1 to 905-Y are positionedrelative to the optical waveguide 901 such that a respective minimumseparation distance between each of the optical microring resonators903-1 to 903-X and 905-1 to 905-Y and the optical waveguide 901 issubstantially the same. However, in some embodiments, the opticalmicroring resonators 903-1 to 903-X and 905-1 to 905-Y are positionedrelative to the optical waveguide 901 such that multiple differentminimum separation distances exist between different ones of the opticalmicroring resonators 903-1 to 903-X and 905-1 to 905-Y and the opticalwaveguide 901.

In various embodiments, the optical microring resonators 903-1 to 903-Xare positioned at a substantially constant pitch (center-to-centerspacing) with respect to each other. However, in other embodiments, theoptical microring resonators 903-1 to 903-X are not positioned at asubstantially constant pitch with respect to each other. Also, invarious embodiments, the optical microring resonators 905-1 to 905-Y arepositioned at a substantially constant pitch with respect to each other.However, in other embodiments, the optical microring resonators 905-1 to905-Y are not positioned at a substantially constant pitch with respectto each other. In some embodiments, the pitch between adjacentlypositioned ones of the optical microring resonators 903-1 to 903-X and905-1 to 905-Y is set at a distance that avoids evanescent coupling oflight between the adjacently positioned ones of the optical microringresonators 903-1 to 903-X and 905-1 to 905-Y. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 903-1 to 903-X and 905-1 to 905-Y is minimized while ensuringthat evanescent coupling of light does not occur between adjacentlypositioned ones of the optical microring resonators 903-1 to 903-X and905-1 to 905-Y. In some embodiments, each of the optical microringresonators 903-1 to 903-X and 905-1 to 905-Y has an outer diametergreater than zero and less than or equal to about 50 micrometers. Insome embodiments, each of the optical microring resonators 903-1 to903-X and 905-1 to 905-Y has an outer diameter greater than zero andless than or equal to about 40 micrometers. In some embodiments, each ofthe optical microring resonators 903-1 to 903-X and 905-1 to 905-Y hasan outer diameter greater than zero and less than or equal to about 30micrometers. In some embodiments, each of the optical microringresonators 903-1 to 903-X and 905-1 to 905-Y has an outer diametergreater than zero and less than or equal to about 20 micrometers. Insome embodiments, each of the optical microring resonators 903-1 to903-X and 905-1 to 905-Y has an outer diameter greater than zero andless than or equal to about 10 micrometers.

The optical microring resonators 903-1 to 903-X are interfaced withelectronic control circuitry 907. The optical microring resonators 905-1to 905-Y are interfaced with electronic control circuitry 909. In someembodiments, the electronic control circuity 907 and 909 includestransmit (Tx) slice circuitry for independently controlling one or moreof the microring resonators 903-1 to 903-X and 905-1 to 905-Y as anoptical modulator to optically modulate light at a given wavelength togenerate a light stream at the given wavelength within the opticalwaveguide 901, where the light stream conveys digital data. In someembodiments, the electronic control circuity 907 and 909 includesreceive (Rx) slice circuitry for independently controlling one or moreof the microring resonators 903-1 to 903-X and 905-1 to 905-Y as anoptical receiver, e.g., photodetector, to detect a modulated lightstream at a given wavelength within the optical waveguide 901 to enablegeneration of electrical signals representing digital data conveyed bythe modulated light stream at the given wavelength. In some embodiments,the electronic control circuity 907 and 909 includes circuitry fordirecting one or more of the microring resonators 903-1 to 903-X and905-1 to 905-Y to operate as an add/drop filter formultiplexing/demultiplexing of optical signals within the opticalwaveguide 901. In some embodiments, the electronic control circuity 907and 909 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 903-1 to 903-Xand 905-1 to 905-Y to enable thermal tuning of the one or more of themicroring resonators 903-1 to 903-X and 905-1 to 905-Y to operate at aparticular resonant optical wavelength. Also, in some embodiments,electronics 911 are formed within the inner region of the U-shapedoptical waveguide 901, where the electronics 911 support operation ofthe optical macro 305-x 1. In some embodiments, the electronics 911include clock signal generation and transmission circuitry, I/Q signalgeneration circuitry, ILO circuitry, PI circuitry, TIA circuitry, signalEQ circuitry, and/or other types of circuitry for supporting operationof the optical macro 305-x 1.

In some embodiments, the optical path layout of the optical macro 305-x1 is optimized by minimizing a length of the optical waveguide 901within the optical macro 305-x 1. The length of the optical waveguide901 within the optical macro 305-x 1 is minimized by having the opticalmicroring resonators 903-1 to 903-X and 905-1 to 905-Y respectivelypositioned along both the first horizontal segment 901A and the secondhorizontal segment 901C of the optical waveguide 901,reducing/constraining the pitch of the optical microring resonators903-1 to 903-X and 905-1 to 905-Y, and having the first and secondoptical ports 902A and 902B of the optical waveguide 901 located on thesame side of the optical macro 305-x 1. However, it should be understoodthat in other embodiments, the optical path layout of the optical macro305-x 1 is configured to have all of the optical microring resonators903-1 to 903-X and 905-1 to 905-Y positioned along a same side of theoptical waveguide 901, e.g. along either the first horizontal segment901A or the second horizontal segment 901C.

FIG. 10 shows an example optical path layout of an optical macro 305-x 2for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a C-shaped optical waveguide 1001, inaccordance with some embodiments. The C-shaped optical waveguide 1001includes a first horizontal (East-West oriented) segment 1001A, a firstcurved segment 1001B, a vertical (North-South oriented) segment 1001C, asecond curved segment 1001D, and a second horizontal (East-Westoriented) segment 1001E. In some embodiments, the first curved segment1001B curves around about 90 degrees from the first horizontal segment1001A to the vertical segment 1001C, vice-versa. In some embodiments,the second curved segment 1001D curves around about 90 degrees from thevertical segment 1001C to the second horizontal segment 1001E,vice-versa. The first horizontal segment 1001A is optically connected toa first optical port 1002A, and the second horizontal segment 1001E isoptically connected to a second optical port 1002B. In variousembodiments, the first optical port 1002A is formed as a verticaloptical grating coupler or a horizontal (edge) optical grating coupler.Also, in various embodiments, the second optical port 1002B is formed asa vertical optical grating coupler or a horizontal (edge) opticalgrating coupler.

In some embodiments, the first horizontal segment 1001A, the firstcurved segment 1001B, the vertical segment 1001C, the second curvedsegment 1001D, and the second horizontal segment 1001E of the opticalwaveguide 1001 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 1001A, the first curved segment 1001B, the verticalsegment 1001C, the second curved segment 1001D, and the secondhorizontal segment 1001E of the optical waveguide 1001 is/are formed ofa different material than one or more others of the first horizontalsegment 1001A, the first curved segment 1001B, the vertical segment1001C, the second curved segment 1001D, and the second horizontalsegment 1001E of the optical waveguide 1001, such that the opticalwaveguide 1001 is formed as a combination of materials, e.g., acombination of two or more of silicon, polysilicon, silicon nitride,and/or any other material suitable for use as an optical waveguide.Also, in some embodiments, each of the first horizontal segment 1001A,the first curved segment 1001B, the vertical segment 1001C, the secondcurved segment 1001D, and the second horizontal segment 1001E of theoptical waveguide 1001 is formed to have a substantially similarvertical cross-section shape. However, in some embodiments, any one ormore of the first horizontal segment 1001A, the first curved segment1001B, the vertical segment 1001C, the second curved segment 1001D, andthe second horizontal segment 1001E of the optical waveguide 1001 is/areformed to have a different vertical cross-section shape than one or moreothers of the first horizontal segment 1001A, the first curved segment1001B, the vertical segment 1001C, the second curved segment 1001D, andthe second horizontal segment 1001E of the optical waveguide 1001. Also,in some embodiments, any one or more of the first horizontal segment1001A, the first curved segment 1001B, the vertical segment 1001C, thesecond curved segment 1001D, and the second horizontal segment 1001E ofthe optical waveguide 1001 is/are formed to have a verticalcross-section shape that varies along its length in the direction oflight propagation through the optical waveguide 1001.

The optical macro 305-x 2 includes optical microring resonators 1003-1to 1003-X (where X is an integer greater than zero) that are opticallycoupled to the vertical segment 1001C of the C-shaped optical waveguide1001, such that light traveling through the optical waveguide 1001 canbe evanescently coupled into the optical microring resonators 1003-1 to1003-X, and such that light traveling through the optical microringresonators 1003-1 to 1003-X can be evanescently coupled into the opticalwaveguide 1001. In some embodiments, the optical macro 305-x 2 does nothave any microring resonator optically coupled to either the firsthorizontal segment 1001A, the first curved segment 1001B, the secondcurved segment 1001D, or the second horizontal segment 1001E of theC-shaped optical waveguide 1001. In some embodiments, all microringresonators, e.g., 1003-1 to 1003-X, within the optical macro 305-x 2 areoptically coupled to the vertical segment 1001C of the C-shaped opticalwaveguide 1001. In some embodiments, each of the optical microringresonators 1003-1 to 1003-X is positioned along a same side/edge thevertical segment 1001C of the C-shaped optical waveguide 1001. Forexample, FIG. 10 shows each of the optical microring resonators 1003-1to 1003-X positioned along the outer side/edge of the vertical segment1001C of the C-shaped optical waveguide 1001. In the example embodimentof FIG. 10, the first curved segment 1001B and the second curved segment1001D are oriented such that the first optical port 1002A and the secondoptical port 1002B are located on a left side (West side) of the opticalmacro 305-x 2. However, in some alternative embodiments, the firstcurved segment 1001B and the second curved segment 1001D are oriented(flipped horizontally) such that the first optical port 1002A and thesecond optical port 1002B are located on a right side (East side) of theoptical macro 305-x 2. In these alternative embodiments, each of theoptical microring resonators 1003-1 to 1003-X is positioned along theinner side/edge of the vertical segment 1001C of the C-shaped opticalwaveguide 1001.

In some embodiments, the optical microring resonators 1003-1 to 1003-Xare positioned relative to the optical waveguide 1001 such that arespective minimum separation distance between each of the opticalmicroring resonators 1003-1 to 1003-X and the optical waveguide 1001 issubstantially the same. However, in some embodiments, the opticalmicroring resonators 1003-1 to 1003-X are positioned relative to theoptical waveguide 1001 such that multiple different minimum separationdistances exist between different ones of the optical microringresonators 1003-1 to 1003-X and the optical waveguide 1001. In variousembodiments, the optical microring resonators 1003-1 to 1003-X arepositioned at a substantially constant pitch with respect to each other.However, in other embodiments, the optical microring resonators 1003-1to 1003-X are not positioned at a substantially constant pitch withrespect to each other. In some embodiments, the pitch between adjacentlypositioned ones of the optical microring resonators 1003-1 to 1003-X isset at a distance that avoids evanescent coupling of light between theadjacently positioned ones of the optical microring resonators 1003-1 to1003-X. In some embodiments, the pitch between adjacently positionedones of the optical microring resonators 1003-1 to 1003-X is minimizedwhile ensuring that evanescent coupling of light does not occur betweenadjacently positioned ones of the optical microring resonators 1003-1 to1003-X. In some embodiments, the optical path layout of the opticalmacro 305-x 2 is optimized by minimizing a length of the opticalwaveguide 1001 within the optical macro 305-x 2. The length of theoptical waveguide 1001 within the optical macro 305-x 2 is minimized byreducing/constraining the pitch of the optical microring resonators1003-1 to 1003-X, and having the first and second optical ports 1002Aand 1002B of the optical waveguide 1001 located on the same side of theoptical macro 305-x 2.

In some embodiments, each of the optical microring resonators 1003-1 to1003-X has an outer diameter greater than zero and less than or equal toabout 50 micrometers. In some embodiments, each of the optical microringresonators 1003-1 to 1003-X has an outer diameter greater than zero andless than or equal to about 40 micrometers. In some embodiments, each ofthe optical microring resonators 1003-1 to 1003-X has an outer diametergreater than zero and less than or equal to about 30 micrometers. Insome embodiments, each of the optical microring resonators 1003-1 to1003-X has an outer diameter greater than zero and less than or equal toabout 20 micrometers. In some embodiments, each of the optical microringresonators 1003-1 to 1003-X has an outer diameter greater than zero andless than or equal to about 10 micrometers.

The optical microring resonators 1003-1 to 1003-X are interfaced withelectronic control circuitry 1005. In some embodiments, the electroniccontrol circuity 1005 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1003-1to 1003-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1001, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1005 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1003-1 to 1003-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1001 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1005 includes circuitry for directing one or more of themicroring resonators 1003-1 to 1003-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1001. In some embodiments, the electronic control circuity1005 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1003-1 to 1003-Xto enable thermal tuning of the one or more of the microring resonators1003-1 to 1003-X to operate at a particular resonant optical wavelength.Also, in some embodiments, electronics 1007 are formed within the innerregion of the C-shaped optical waveguide 1001, where the electronics1007 support operation of the optical macro 305-x 2. In someembodiments, the electronics 1007 include clock signal generation andtransmission circuitry, I/Q signal generation circuitry, ILO circuitry,PI circuitry, TIA circuitry, signal EQ circuitry, and/or other types ofcircuitry for supporting operation of the optical macro 305-x 2.

FIG. 11 shows an example optical path layout of an optical macro 305-x 3for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a C-shaped optical waveguide 1101, inaccordance with some embodiments. The C-shaped optical waveguide 1101includes a first horizontal (East-West oriented) segment 1101A, a firstcurved segment 1101B, a vertical (North-South oriented) segment 1101C, asecond curved segment 1101D, and a second horizontal (East-Westoriented) segment 1101E. In some embodiments, the first curved segment1101B curves around about 90 degrees from the first horizontal segment1101A to the vertical segment 1101C, vice-versa. In some embodiments,the second curved segment 1101D curves around about 90 degrees from thevertical segment 1101C to the second horizontal segment 1101E,vice-versa. The first horizontal segment 1101A is optically connected toa first optical port 1102A, and the second horizontal segment 1101E isoptically connected to a second optical port 1102B. In variousembodiments, the first optical port 1102A is formed as a verticaloptical grating coupler or a horizontal (edge) optical grating coupler.Also, in various embodiments, the second optical port 1102B is formed asa vertical optical grating coupler or a horizontal (edge) opticalgrating coupler.

In some embodiments, the first horizontal segment 1101A, the firstcurved segment 1101B, the vertical segment 1101C, the second curvedsegment 1101D, and the second horizontal segment 1101E of the opticalwaveguide 1101 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 1101A, the first curved segment 1101B, the verticalsegment 1101C, the second curved segment 1101D, and the secondhorizontal segment 1101E of the optical waveguide 1101 is/are formed ofa different material than one or more others of the first horizontalsegment 1101A, the first curved segment 1101B, the vertical segment1101C, the second curved segment 1101D, and the second horizontalsegment 1101E of the optical waveguide 1101, such that the opticalwaveguide 1101 is formed as a combination of materials, e.g., acombination of two or more of silicon, polysilicon, silicon nitride,and/or any other material suitable for use as an optical waveguide.Also, in some embodiments, each of the first horizontal segment 1101A,the first curved segment 1101B, the vertical segment 1101C, the secondcurved segment 1101D, and the second horizontal segment 1101E of theoptical waveguide 1101 is formed to have a substantially similarvertical cross-section shape. However, in some embodiments, any one ormore of the first horizontal segment 1101A, the first curved segment1101B, the vertical segment 1101C, the second curved segment 1101D, andthe second horizontal segment 1101E of the optical waveguide 1101 is/areformed to have a different vertical cross-section shape than one or moreothers of the first horizontal segment 1101A, the first curved segment1101B, the vertical segment 1101C, the second curved segment 1101D, andthe second horizontal segment 1101E of the optical waveguide 1101. Also,in some embodiments, any one or more of the first horizontal segment1101A, the first curved segment 1101B, the vertical segment 1101C, thesecond curved segment 1101D, and the second horizontal segment 1101E ofthe optical waveguide 1101 is/are formed to have a verticalcross-section shape that varies along its length in the direction oflight propagation through the optical waveguide 1101.

The optical macro 305-x 3 includes optical microring resonators 1103-1to 1103-X (where X is an integer greater than zero) that are opticallycoupled to the first horizontal segment 1101A of the C-shaped opticalwaveguide 1101, such that light traveling through the optical waveguide1101 can be evanescently coupled into the optical microring resonators1103-1 to 1103-X, and such that light traveling through the opticalmicroring resonators 1103-1 to 1103-X can be evanescently coupled intothe optical waveguide 1101. The optical macro 305-x 3 includes opticalmicroring resonators 1105-1 to 1105-Y (where Y is an integer greaterthan zero) that are optically coupled to the vertical segment 1101C ofthe C-shaped optical waveguide 1101, such that light traveling throughthe optical waveguide 1101 can be evanescently coupled into the opticalmicroring resonators 1105-1 to 1105-Y, and such that light travelingthrough the optical microring resonators 1105-1 to 1105-Y can beevanescently coupled into the optical waveguide 1101. The optical macro305-x 3 also includes optical microring resonators 1107-1 to 1107-Z(where Z is an integer greater than zero) that are optically coupled tothe second horizontal segment 1101E of the C-shaped optical waveguide1101, such that light traveling through the optical waveguide 1101 canbe evanescently coupled into the optical microring resonators 1107-1 to1107-Z, and such that light traveling through the optical microringresonators 1107-1 to 1107-Z can be evanescently coupled into the opticalwaveguide 1101. In the optical layout of the optical macro 305-x 3, eachof the optical microring resonators 1103-1 to 1103-X, 1105-1 to 1105-Y,and 1107-1 to 1107-Z is positioned along an outer side/edge of theC-shaped optical waveguide 1101. In some embodiments, the opticalmicroring resonators 1103-1 to 1103-X, 1105-1 to 1105-Y, and 1107-1 to1107-Z are positioned relative to the optical waveguide 1101 such that arespective minimum separation distance between each of the opticalmicroring resonators 1103-1 to 1103-X, 1105-1 to 1105-Y, and 1107-1 to1107-Z and the optical waveguide 1101 is substantially the same.However, in some embodiments, the optical microring resonators 1103-1 to1103-X, 1105-1 to 1105-Y, and 1107-1 to 1107-Z are positioned relativeto the optical waveguide 1101 such that multiple different minimumseparation distances exist between different ones of the opticalmicroring resonators 1103-1 to 1103-X, 1105-1 to 1105-Y, and 1107-1 to1107-Z and the optical waveguide 1101.

In various embodiments, the optical microring resonators 1103-1 to1103-X are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1103-1 to 1103-X are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1103-1 to 1103-X is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1103-1 to 1103-X. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1103-1 to 1103-X is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1103-1 to 1103-X.

In various embodiments, the optical microring resonators 1105-1 to1105-Y are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1105-1 to 1105-Y are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1105-1 to 1105-Y is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1105-1 to 1105-Y. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1105-1 to 1105-Y is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1105-1 to 1105-Y.

In various embodiments, the optical microring resonators 1107-1 to1107-Z are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1107-1 to 1107-Z are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1107-1 to 1107-Z is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1107-1 to 1107-Z. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1107-1 to 1107-Z is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1107-1 to 1107-Z.

In some embodiments, the optical path layout of the optical macro 305-x3 is optimized by minimizing a length of the optical waveguide 1101within the optical macro 305-x 3. The length of the optical waveguide1001 within the optical macro 305-x 3 is minimized byreducing/constraining the pitch of the optical microring resonators1103-1 to 1103-X, reducing/constraining the pitch of the opticalmicroring resonators 1105-1 to 1105-Y, reducing/constraining the pitchof the optical microring resonators 1107-1 to 1107-Z, and having thefirst and second optical ports 1102A and 1102B of the optical waveguide1001 located on the same side of the optical macro 305-x 3. In someembodiments, each of the optical microring resonators 1103-1 to 1103-X,1105-1 to 1105-Y, and 1107-1 to 1107-Z has an outer diameter greaterthan zero and less than or equal to about 50 micrometers. In someembodiments, each of the optical microring resonators 1103-1 to 1103-X,1105-1 to 1105-Y, and 1107-1 to 1107-Z has an outer diameter greaterthan zero and less than or equal to about 40 micrometers. In someembodiments, each of the optical microring resonators 1103-1 to 1103-X,1105-1 to 1105-Y, and 1107-1 to 1107-Z has an outer diameter greaterthan zero and less than or equal to about 30 micrometers. In someembodiments, each of the optical microring resonators 1103-1 to 1103-X,1105-1 to 1105-Y, and 1107-1 to 1107-Z has an outer diameter greaterthan zero and less than or equal to about 20 micrometers. In someembodiments, each of the optical microring resonators 1103-1 to 1103-X,1105-1 to 1105-Y, and 1107-1 to 1107-Z has an outer diameter greaterthan zero and less than or equal to about 10 micrometers.

The optical microring resonators 1103-1 to 1103-X are interfaced withelectronic control circuitry 1109. In some embodiments, the electroniccontrol circuity 1109 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1103-1to 1103-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1101, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1109 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1103-1 to 1103-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1101 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1109 includes circuitry for directing one or more of themicroring resonators 1103-1 to 1103-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1101. In some embodiments, the electronic control circuity1109 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1103-1 to 1103-Xto enable thermal tuning of the one or more of the microring resonators1103-1 to 1103-X to operate at a particular resonant optical wavelength.

The optical microring resonators 1105-1 to 1105-Y are interfaced withelectronic control circuitry 1111. In some embodiments, the electroniccontrol circuity 1111 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1105-1to 1105-Y as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1101, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1111 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1105-1 to 1105-Y as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1101 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1111 includes circuitry for directing one or more of themicroring resonators 1105-1 to 1105-Y to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1101. In some embodiments, the electronic control circuity1111 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1105-1 to 1105-Yto enable thermal tuning of the one or more of the microring resonators1105-1 to 1105-Y to operate at a particular resonant optical wavelength.

The optical microring resonators 1107-1 to 1107-Z are interfaced withelectronic control circuitry 1113. In some embodiments, the electroniccontrol circuity 1113 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1107-1to 1107-Z as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1101, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1113 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1107-1 to 1107-Z as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1101 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1113 includes circuitry for directing one or more of themicroring resonators 1107-1 to 1107-Z to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1101. In some embodiments, the electronic control circuity1113 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1107-1 to 1107-Zto enable thermal tuning of the one or more of the microring resonators1107-1 to 1107-Z to operate at a particular resonant optical wavelength.

Also, in some embodiments, electronics 1115 are formed within the innerregion of the C-shaped optical waveguide 1101, where the electronics1115 support operation of the optical macro 305-x 3. In someembodiments, the electronics 1115 include clock signal generation andtransmission circuitry, I/Q signal generation circuitry, ILO circuitry,PI circuitry, TIA circuitry, signal EQ circuitry, and/or other types ofcircuitry for supporting operation of the optical macro 305-x 3.

FIG. 12 shows an example optical path layout of an optical macro 305-x 4for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a C-shaped optical waveguide 1201, inaccordance with some embodiments. The C-shaped optical waveguide 1201includes a first horizontal (East-West oriented) segment 1201A, a firstcurved segment 1201B, a vertical (North-South oriented) segment 1201C, asecond curved segment 1201D, and a second horizontal (East-Westoriented) segment 1201E. In some embodiments, the first curved segment1201B curves around about 90 degrees from the first horizontal segment1201A to the vertical segment 1201C, vice-versa. In some embodiments,the second curved segment 1201D curves around about 90 degrees from thevertical segment 1201C to the second horizontal segment 1201E,vice-versa. The first horizontal segment 1201A is optically connected toa first optical port 1202A, and the second horizontal segment 1201E isoptically connected to a second optical port 1202B. In variousembodiments, the first optical port 1202A is formed as a verticaloptical grating coupler or a horizontal (edge) optical grating coupler.Also, in various embodiments, the second optical port 1202B is formed asa vertical optical grating coupler or a horizontal (edge) opticalgrating coupler.

In some embodiments, the first horizontal segment 1201A, the firstcurved segment 1201B, the vertical segment 1201C, the second curvedsegment 1201D, and the second horizontal segment 1201E of the opticalwaveguide 1201 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 1201A, the first curved segment 1201B, the verticalsegment 1201C, the second curved segment 1201D, and the secondhorizontal segment 1201E of the optical waveguide 1201 is/are formed ofa different material than one or more others of the first horizontalsegment 1201A, the first curved segment 1201B, the vertical segment1201C, the second curved segment 1201D, and the second horizontalsegment 1201E of the optical waveguide 1201, such that the opticalwaveguide 1201 is formed as a combination of materials, e.g., acombination of two or more of silicon, polysilicon, silicon nitride,and/or any other material suitable for use as an optical waveguide.Also, in some embodiments, each of the first horizontal segment 1201A,the first curved segment 1201B, the vertical segment 1201C, the secondcurved segment 1201D, and the second horizontal segment 1201E of theoptical waveguide 1201 is formed to have a substantially similarvertical cross-section shape. However, in some embodiments, any one ormore of the first horizontal segment 1201A, the first curved segment1201B, the vertical segment 1201C, the second curved segment 1201D, andthe second horizontal segment 1201E of the optical waveguide 1201 is/areformed to have a different vertical cross-section shape than one or moreothers of the first horizontal segment 1201A, the first curved segment1201B, the vertical segment 1201C, the second curved segment 1201D, andthe second horizontal segment 1201E of the optical waveguide 1201. Also,in some embodiments, any one or more of the first horizontal segment1201A, the first curved segment 1201B, the vertical segment 1201C, thesecond curved segment 1201D, and the second horizontal segment 1201E ofthe optical waveguide 1201 is/are formed to have a verticalcross-section shape that varies along its length in the direction oflight propagation through the optical waveguide 1201.

The optical macro 305-x 4 includes optical microring resonators 1203-1to 1203-X (where X is an integer greater than zero) that are opticallycoupled to the vertical segment 1201C of the C-shaped optical waveguide1201, such that light traveling through the optical waveguide 1201 canbe evanescently coupled into the optical microring resonators 1203-1 to1203-X, and such that light traveling through the optical microringresonators 1203-1 to 1203-X can be evanescently coupled into the opticalwaveguide 1201. The optical macro 305-x 4 also includes opticalmicroring resonators 1205-1 to 1205-Y (where Y is an integer greaterthan zero) that are optically coupled to the vertical segment 1201C ofthe C-shaped optical waveguide 1201, such that light traveling throughthe optical waveguide 1201 can be evanescently coupled into the opticalmicroring resonators 1205-1 to 1205-Y, and such that light travelingthrough the optical microring resonators 1205-1 to 1205-Y can beevanescently coupled into the optical waveguide 1201. The opticalmicroring resonators 1203-1 to 1203-X are positioned along an outerside/edge of the optical waveguide 1201. The optical microringresonators 1205-1 to 1205-Y are positioned along an inner side/edge ofthe optical waveguide 1201. In some embodiments, the optical microringresonators 1203-1 to 1203-X and 1205-1 to 1205-Y are positioned so thatoptical coupling locations between the optical microring resonators1203-1 to 1203-X and the optical waveguide 1201 are offset/staggeredfrom (do not overlap with) optical coupling locations between theoptical microring resonators 1205-1 to 1205-Y and the optical waveguide1201. In this manner, the optical microring resonators 1203-1 to 1203-Xand 1205-1 to 1205-Y do not optically couple to the same location alongoptical waveguide 1201 in order to avoid optical intercoupling betweendifferent ones of the optical microring resonators 1203-1 to 1203-X and1205-1 to 1205-Y. In some embodiments, the optical macro 305-x 4 doesnot have any microring resonator optically coupled to either the firsthorizontal segment 1201A, the first curved segment 1201B, the secondcurved segment 1201D, or the second horizontal segment 1201E of theC-shaped optical waveguide 1201. In some embodiments, all microringresonators, e.g., 1203-1 to 1203-X and 1205-1 to 1205-Y, within theoptical macro 305-x 4 are optically coupled to the vertical segment1201C of the C-shaped optical waveguide 1201.

In some embodiments, the optical microring resonators 1203-1 to 1203-Xand 1205-1 to 1205-Y are positioned relative to the optical waveguide1201 such that a respective minimum separation distance between each ofthe optical microring resonators 1203-1 to 1203-X and 1205-1 to 1205-Yand the optical waveguide 1201 is substantially the same. However, insome embodiments, the optical microring resonators 1203-1 to 1203-X and1205-1 to 1205-Y are positioned relative to the optical waveguide 1201such that multiple different minimum separation distances exist betweendifferent ones of the optical microring resonators 1203-1 to 1203-X and1205-1 to 1205-Y and the optical waveguide 1201. In various embodiments,the optical microring resonators 1203-1 to 1203-X are positioned at asubstantially constant pitch with respect to each other. However, inother embodiments, the optical microring resonators 1203-1 to 1203-X arenot positioned at a substantially constant pitch with respect to eachother. In some embodiments, the pitch between adjacently positioned onesof the optical microring resonators 1203-1 to 1203-X is set at adistance that avoids evanescent coupling of light between the adjacentlypositioned ones of the optical microring resonators 1203-1 to 1203-X. Insome embodiments, the pitch between adjacently positioned ones of theoptical microring resonators 1203-1 to 1203-X is minimized whileensuring that evanescent coupling of light does not occur betweenadjacently positioned ones of the optical microring resonators 1203-1 to1203-X. In various embodiments, the optical microring resonators 1205-1to 1205-Y are positioned at a substantially constant pitch with respectto each other. However, in other embodiments, the optical microringresonators 1205-1 to 1205-Y are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1205-1 to 1205-Y is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1205-1 to 1205-Y. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1205-1 to 1205-Y is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1205-1 to 1205-Y. In some embodiments, the opticalpath layout of the optical macro 305-x 4 is optimized by minimizing alength of the optical waveguide 1201 within the optical macro 305-x 4.The length of the optical waveguide 1201 within the optical macro 305-x4 is minimized by reducing/constraining the pitch of the opticalmicroring resonators 1203-1 to 1203-X, reducing/constraining the pitchof the optical microring resonators 1205-1 to 1205-Y, and having thefirst and second optical ports 1002A and 1002B of the optical waveguide1201 located on the same side of the optical macro 305-x 4.

In some embodiments, each of the optical microring resonators 1203-1 to1203-X and 1205-1 to 1205-Y has an outer diameter greater than zero andless than or equal to about 50 micrometers. In some embodiments, each ofthe optical microring resonators 1203-1 to 1203-X and 1205-1 to 1205-Yhas an outer diameter greater than zero and less than or equal to about40 micrometers. In some embodiments, each of the optical microringresonators 1203-1 to 1203-X and 1205-1 to 1205-Y has an outer diametergreater than zero and less than or equal to about 30 micrometers. Insome embodiments, each of the optical microring resonators 1203-1 to1203-X and 1205-1 to 1205-Y has an outer diameter greater than zero andless than or equal to about 20 micrometers. In some embodiments, each ofthe optical microring resonators 1203-1 to 1203-X and 1205-1 to 1205-Yhas an outer diameter greater than zero and less than or equal to about10 micrometers.

The optical microring resonators 1203-1 to 1203-X are interfaced withelectronic control circuitry 1207. In some embodiments, the electroniccontrol circuity 1207 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1203-1to 1203-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1201, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1207 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1203-1 to 1203-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1201 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1207 includes circuitry for directing one or more of themicroring resonators 1203-1 to 1203-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1201. In some embodiments, the electronic control circuity1207 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1203-1 to 1203-Xto enable thermal tuning of the one or more of the microring resonators1203-1 to 1203-X to operate at a particular resonant optical wavelength.

The optical microring resonators 1205-1 to 1205-Y are interfaced withelectronic control circuitry 1209. In some embodiments, the electroniccontrol circuity 1209 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1205-1to 1205-Y as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1201, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1209 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1205-1 to 1205-Y as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1201 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1209 includes circuitry for directing one or more of themicroring resonators 1205-1 to 1205-Y to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1201. In some embodiments, the electronic control circuity1209 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1205-1 to 1205-Yto enable thermal tuning of the one or more of the microring resonators1205-1 to 1205-Y to operate at a particular resonant optical wavelength.Also, in some embodiments, the electronic control circuitry 1207 and/orthe electronic control circuitry 1209 include electroniccomponents/circuitry for supporting operation of the optical macro 305-x4, such as clock signal generation and transmission circuitry, I/Qsignal generation circuitry, ILO circuitry, PI circuitry, TIA circuitry,signal EQ circuitry, and/or other types of circuitry.

It should be understood that the U-shaped optical waveguide 901 of FIG.9 and the C-shaped optical waveguides 1001, 1101, and 1201 of FIGS. 10,11, and 12, respectively, are configured to receive input light andtransmit output light on a same side of the optical macro 305-x. Morespecifically, the input port and the output port of the U/C-shapedoptical waveguides 901, 1001, 1101, and 1201 are positioned on a sameside of the optical macro 305-x. Therefore, the U/C-shaped opticalwaveguides 901, 1001, 1101, and 1201 are suitable for optical packageescape configurations in which light both enters and exits on the sameside of the TeraPHY optical I/O chiplet 107. Also, it should beunderstood that the inner area between the horizontal segments of theU/C-shaped optical waveguides 901, 1001, 1101, and 1201 can includeelectronics, when the inner area is of sufficient size and shape.

In some embodiments, it is advantageous for the optical waveguide portsof the optical macro 305-x to be on different sides of the optical macro305-x, such as on opposite sides (coming out in opposite directions) oron adjacent sides (coming out at a 90 degree offset relative to eachother). FIGS. 13, 14, 15, and 16 show example optical path layouts ofthe optical macro 305-x of the TeraPHY optical I/O chiplet 107 in whichoptical waveguide ports are located on different sides of the opticalmacro 305-x.

FIG. 13 shows an example optical path layout of an optical macro 305-x 5for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a substantially linear-shaped opticalwaveguide 1301 with corresponding optical ports 1302A and 1302B locatedon opposite sides of the optical macro 305-x 5, in accordance with someembodiments. The optical port 1302A is located on the left side (Westside) of the optical macro 305-x 5, and the optical port 1302B islocated on the right side (East side) of the optical macro 305-x 5. Invarious embodiments, the first optical port 1302A is formed as avertical optical grating coupler or a horizontal (edge) optical gratingcoupler. Also, in various embodiments, the second optical port 1302B isformed as a vertical optical grating coupler or a horizontal (edge)optical grating coupler.

In some embodiments, the optical waveguide 1301 is formed of a singlematerial, such as silicon, polysilicon, silicon nitride, or any othermaterial suitable for use as an optical waveguide. In some embodiments,different segments of the optical waveguide 1301 are formed of differentmaterials, such that the optical waveguide 1301 is formed as acombination of materials, e.g., a combination of two or more of silicon,polysilicon, silicon nitride, and/or any other material suitable for useas an optical waveguide. Also, in some embodiments, the opticalwaveguide 1301 is formed to have a substantially constant verticalcross-section shape. However, in some embodiments, different segments ofthe optical waveguide 1301 are formed to have different verticalcross-section shapes. Also, in some embodiments, the verticalcross-section shape of the optical waveguide 1301 varies along itslength in the direction of light propagation through the opticalwaveguide 1301.

The optical macro 305-x 5 includes optical microring resonators 1303-1to 1303-X (where X is an integer greater than zero) that are opticallycoupled to the optical waveguide 1301, such that light traveling throughthe optical waveguide 1301 can be evanescently coupled into the opticalmicroring resonators 1303-1 to 1303-X, and such that light travelingthrough the optical microring resonators 1303-1 to 1303-X can beevanescently coupled into the optical waveguide 1301. In someembodiments, each of the optical microring resonators 1303-1 to 1303-Xis positioned along a same side/edge the optical waveguide 1301. Forexample, FIG. 13 shows each of the optical microring resonators 1303-1to 1303-X positioned along the upper (North) side/edge of the opticalwaveguide 1301. In some embodiments, the optical microring resonators1303-1 to 1303-X are positioned relative to the optical waveguide 1301such that a respective minimum separation distance between each of theoptical microring resonators 1303-1 to 1303-X and the optical waveguide1301 is substantially the same. However, in some embodiments, theoptical microring resonators 1303-1 to 1303-X are positioned relative tothe optical waveguide 1301 such that multiple different minimumseparation distances exist between different ones of the opticalmicroring resonators 1303-1 to 1303-X and the optical waveguide 1301.

In some embodiments, the optical microring resonators 1303-1 to 1303-Xare positioned so as to not optically couple to the same location alongthe optical waveguide 1301 in order to avoid intercoupling betweendifferent ones of the optical microring resonators 1303-1 to 1303-X. Invarious embodiments, the optical microring resonators 1303-1 to 1303-Xare positioned at a substantially constant pitch (center-to-centerspacing) with respect to each other. However, in other embodiments, theoptical microring resonators 1303-1 to 1303-X are not positioned at asubstantially constant pitch with respect to each other. In someembodiments, the pitch between adjacently positioned ones of the opticalmicroring resonators 1303-1 to 1303-X is set at a distance that avoidsevanescent coupling of light between the adjacently positioned ones ofthe optical microring resonators 1303-1 to 1303-X. In some embodiments,the pitch between adjacently positioned ones of the optical microringresonators 1303-1 to 1303-X is minimized while ensuring that evanescentcoupling of light does not occur between adjacently positioned ones ofthe optical microring resonators 1303-1 to 1303-X. In some embodiments,the optical path layout of the optical macro 305-x 5 is optimized byminimizing a length of the optical waveguide 1301 within the opticalmacro 305-x 5. In some embodiments, the length of the optical waveguide1301 within the optical macro 305-x 5 is minimized byreducing/constraining the pitch of the optical microring resonators1303-1 to 1303-X.

In some embodiments, each of the optical microring resonators 1303-1 to1303-X has an outer diameter greater than zero and less than or equal toabout 50 micrometers. In some embodiments, each of the optical microringresonators 1303-1 to 1303-X has an outer diameter greater than zero andless than or equal to about 40 micrometers. In some embodiments, each ofthe optical microring resonators 1303-1 to 1303-X has an outer diametergreater than zero and less than or equal to about 30 micrometers. Insome embodiments, each of the optical microring resonators 1303-1 to1303-X has an outer diameter greater than zero and less than or equal toabout 20 micrometers. In some embodiments, each of the optical microringresonators 1303-1 to 1303-X has an outer diameter greater than zero andless than or equal to about 10 micrometers.

The optical microring resonators 1303-1 to 1303-X are interfaced withelectronic control circuitry 1305. In some embodiments, the electroniccontrol circuity 1305 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1303-1to 1303-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1301, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1305 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1303-1 to 1303-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1301 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1305 includes circuitry for directing one or more of themicroring resonators 1303-1 to 1303-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1301. In some embodiments, the electronic control circuity1305 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1303-1 to 1303-Xto enable thermal tuning of the one or more of the microring resonators1303-1 to 1303-X. Also, in some embodiments, the optical macro 305-x 5includes additional electronics to support operation of the opticalmacro 305-x 5, such as clock signal generation and transmissioncircuitry, I/Q signal generation circuitry, ILO circuitry, PI circuitry,TIA circuitry, signal EQ circuitry, and/or other types of circuitry forsupporting operation of the optical macro 305-x 5.

FIG. 14 shows an example optical path layout of an optical macro 305-x 6for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes an S-shaped optical waveguide 1401, inaccordance with some embodiments. The optical waveguide 1401 includes afirst horizontal (East-West oriented) segment 1401A, a first curvedsegment 1401B, a second horizontal (East-West oriented) segment 1401C, asecond curved segment 1401D, and a third horizontal (East-West oriented)segment 1401E. In some embodiments, the first curved segment 1401Bcurves around about 180 degrees from the first horizontal segment 1401Ato the second horizontal segment 1401C, vice-versa. In some embodiments,the second curved segment 1401D curves around about 180 degrees from thesecond horizontal segment 1401C to the third horizontal segment 1401E,vice-versa. The first horizontal segment 1401A is optically connected toa first optical port 1402A. The third horizontal segment 1401E isoptically connected to a second optical port 1402B. The first opticalport 1402A and the second optical port 1402B are located on oppositesides of the optical macro 305-x 6. The first optical port 1402A islocated on the left side (West side) of the optical macro 305-x 6, andthe optical port 1402B is located on the right side (East side) of theoptical macro 305-x 6. In various embodiments, the first optical port1402A is formed as a vertical optical grating coupler or a horizontal(edge) optical grating coupler. Also, in various embodiments, the secondoptical port 1402B is formed as a vertical optical grating coupler or ahorizontal (edge) optical grating coupler.

In some embodiments, the first horizontal segment 1401A, the firstcurved segment 1401B, the second horizontal segment 1401C, the secondcurved segment 1401D, and the third horizontal segment 1401E of theoptical waveguide 1401 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 1401A, the first curved segment 1401B, the secondhorizontal segment 1401C, the second curved segment 1401D, and the thirdhorizontal segment 1401E of the optical waveguide 1401 is/are formed ofa different material than one or more others of the first horizontalsegment 1401A, the first curved segment 1401B, the second horizontalsegment 1401C, the second curved segment 1401D, and the third horizontalsegment 1401E of the optical waveguide 1401, such that the opticalwaveguide 1401 is formed as a combination of materials, e.g., acombination of two or more of silicon, polysilicon, silicon nitride,and/or any other material suitable for use as an optical waveguide.Also, in some embodiments, each of the first horizontal segment 1401A,the first curved segment 1401B, the second horizontal segment 1401C, thesecond curved segment 1401D, and the third horizontal segment 1401E ofthe optical waveguide 1401 is formed to have a substantially similarvertical cross-section shape. However, in some embodiments, any one ormore of the first horizontal segment 1401A, the first curved segment1401B, the second horizontal segment 1401C, the second curved segment1401D, and the third horizontal segment 1401E of the optical waveguide1401 is/are formed to have a different vertical cross-section shape thanone or more others of the first horizontal segment 1401A, the firstcurved segment 1401B, the second horizontal segment 1401C, the secondcurved segment 1401D, and the third horizontal segment 1401E of theoptical waveguide 1401. Also, in some embodiments, any one or more ofthe first horizontal segment 1401A, the first curved segment 1401B, thesecond horizontal segment 1401C, the second curved segment 1401D, andthe third horizontal segment 1401E of the optical waveguide 1401 is/areformed to have a vertical cross-section shape that varies along itslength in the direction of light propagation through the opticalwaveguide 1401.

The optical macro 305-x 6 includes optical microring resonators 1403-1to 1403-X (where X is an integer greater than zero) that are opticallycoupled to the first horizontal segment 1401A of the S-shaped opticalwaveguide 1401, such that light traveling through the optical waveguide1401 can be evanescently coupled into the optical microring resonators1403-1 to 1403-X, and such that light traveling through the opticalmicroring resonators 1403-1 to 1403-X can be evanescently coupled intothe optical waveguide 1401. The optical macro 305-x 6 also includesoptical microring resonators 1405-1 to 1405-Y (where Y is an integergreater than zero) that are optically coupled to the second horizontalsegment 1401C of the S-shaped optical waveguide 1401, such that lighttraveling through the optical waveguide 1401 can be evanescently coupledinto the optical microring resonators 1405-1 to 1405-Y, and such thatlight traveling through the optical microring resonators 1405-1 to1405-Y can be evanescently coupled into the optical waveguide 1401. Theoptical macro 305-x 6 also includes optical microring resonators 1407-1to 1407-Z (where Z is an integer greater than zero) that are opticallycoupled to the third horizontal segment 1401E of the S-shaped opticalwaveguide 1401, such that light traveling through the optical waveguide1401 can be evanescently coupled into the optical microring resonators1407-1 to 1407-Z, and such that light traveling through the opticalmicroring resonators 1407-1 to 1407-Z can be evanescently coupled intothe optical waveguide 1401.

The optical macro 305-x 6 shows a particular example of an opticallayout in which each of the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z is optically coupled toone of the three horizontal segments 1401A, 1401C, and 1401E of theS-shaped optical waveguide 1401. In some embodiments, the opticalmicroring resonators 1403-1 to 1403-X, 1405-1 to 1405-Y, and 1407-1 to1407-Z are positioned relative to the optical waveguide 1401 such that arespective minimum separation distance between each of the opticalmicroring resonators 1403-1 to 1403-X, 1405-1 to 1405-Y, and 1407-1 to1407-Z and the optical waveguide 1401 is substantially the same.However, in some embodiments, the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z are positioned relativeto the optical waveguide 1401 such that multiple different minimumseparation distances exist between different ones of the opticalmicroring resonators 1403-1 to 1403-X, 1405-1 to 1405-Y, and 1407-1 to1407-Z and the optical waveguide 1401.

In various embodiments, the optical microring resonators 1403-1 to1403-X are positioned at a substantially constant pitch(center-to-center spacing) with respect to each other. However, in otherembodiments, the optical microring resonators 1403-1 to 1403-X are notpositioned at a substantially constant pitch with respect to each other.In some embodiments, the pitch between adjacently positioned ones of theoptical microring resonators 1403-1 to 1403-X is set at a distance thatavoids evanescent coupling of light between the adjacently positionedones of the optical microring resonators 1403-1 to 1403-X. In someembodiments, the pitch between adjacently positioned ones of the opticalmicroring resonators 1403-1 to 1403-X is minimized while ensuring thatevanescent coupling of light does not occur between adjacentlypositioned ones of the optical microring resonators 1403-1 to 1403-X. Insome embodiments, the optical microring resonators 1403-1 to 1403-X donot optically couple to the same location along optical waveguide 1401in order to avoid optical intercoupling between different ones of theoptical microring resonators 1403-1 to 1403-X.

Also, in various embodiments, the optical microring resonators 1405-1 to1405-Y are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1405-1 to 1405-Y are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1405-1 to 1405-Y is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1405-1 to 1405-Y. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1405-1 to 1405-Y is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1405-1 to 1405-Y. In some embodiments, the opticalmicroring resonators 1405-1 to 1405-Y do not optically couple to thesame location along optical waveguide 1401 in order to avoid opticalintercoupling between different ones of the optical microring resonators1405-1 to 1405-Y.

Also, in various embodiments, the optical microring resonators 1407-1 to1407-Z are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1407-1 to 1407-Z are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1407-1 to 1407-Z is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1407-1 to 1407-Z. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1407-1 to 1407-Z is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1407-1 to 1407-Z. In some embodiments, the opticalmicroring resonators 1407-1 to 1407-Z do not optically couple to thesame location along optical waveguide 1401 in order to avoid opticalintercoupling between different ones of the optical microring resonators1407-1 to 1407-Z.

In some embodiments, each of the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z has an outer diametergreater than zero and less than or equal to about 50 micrometers. Insome embodiments, each of the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z has an outer diametergreater than zero and less than or equal to about 40 micrometers. Insome embodiments, each of the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z has an outer diametergreater than zero and less than or equal to about 30 micrometers. Insome embodiments, each of the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z has an outer diametergreater than zero and less than or equal to about 20 micrometers. Insome embodiments, each of the optical microring resonators 1403-1 to1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z has an outer diametergreater than zero and less than or equal to about 10 micrometers.

The optical microring resonators 1403-1 to 1403-X are interfaced withelectronic control circuitry 1409. In some embodiments, the electroniccontrol circuity 1409 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1403-1to 1403-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1401, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1409 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1403-1 to 1403-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1401 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1409 includes circuitry for directing one or more of themicroring resonators 1403-1 to 1403-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1401. In some embodiments, the electronic control circuity1409 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1403-1 to 1403-Xto enable thermal tuning of the one or more of the microring resonators1403-1 to 1403-X.

The optical microring resonators 1405-1 to 1405-Y are interfaced withelectronic control circuitry 1411. In some embodiments, the electroniccontrol circuity 1411 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1405-1to 1405-Y as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1401, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1411 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1405-1 to 1405-Y as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1401 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1411 includes circuitry for directing one or more of themicroring resonators 1405-1 to 1405-Y to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1401. In some embodiments, the electronic control circuity1411 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1405-1 to 1405-Yto enable thermal tuning of the one or more of the microring resonators1405-1 to 1405-Y.

The optical microring resonators 1407-1 to 1407-Z are interfaced withelectronic control circuitry 1413. In some embodiments, the electroniccontrol circuity 1413 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1407-1to 1407-Z as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1401, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1413 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1407-1 to 1407-Z as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1401 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1413 includes circuitry for directing one or more of themicroring resonators 1407-1 to 1407-Z to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1401. In some embodiments, the electronic control circuity1413 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1407-1 to 1407-Zto enable thermal tuning of the one or more of the microring resonators1407-1 to 1407-Z. Also, in some embodiments, the optical macro 305-x 6includes additional electronics to support operation of the opticalmacro 305-x 6, such as clock signal generation and transmissioncircuitry, I/Q signal generation circuitry, ILO circuitry, PI circuitry,TIA circuitry, signal EQ circuitry, and/or other types of circuitry forsupporting operation of the optical macro 305-x 6.

In some embodiments, the optical path layout of the optical macro 305-x6 is optimized by minimizing a length of the optical waveguide 1401within the optical macro 305-x 6. The length of the optical waveguide1401 within the optical macro 305-x 6 is minimized by having the opticalmicroring resonators 1403-1 to 1403-X, 1405-1 to 1405-Y, and 1407-1 to1407-Z respectively positioned along each of the first horizontalsegment 1401A, the second horizontal segment 1401C, and the thirdhorizontal segment 1401E of the optical waveguide 1401, andreducing/constraining the pitch of the optical microring resonators1403-1 to 1403-X, 1405-1 to 1405-Y, and 1407-1 to 1407-Z. In someembodiments of the optical path layout of the optical macro 305-x 6 oneor more additional optical microring resonators are positioned along thefirst curved segment 1401B and/or the second curved segment 1401D, sothat the one or more additional optical microring resonators opticallycouple with the optical waveguide 1401. It should be understood that invarious embodiments the optical path layout of the optical macro 305-x 6can be modified so that the S-shaped optical waveguide 1401 becomes aserpentine-shaped optical waveguide that includes essentially any numberof horizontal linear-shaped segments and any number of curved segments,with essentially any number of optical microring resonators positionedalong the serpentine-shaped optical waveguide so as to optically couplewith the serpentine-shaped optical waveguide. Moreover, in someembodiments, the different horizontal linear-shaped segments and/orcurved segments of the serpentine-shaped optical waveguide can havedifferent lengths, such that different numbers of optical microringresonators are positioned along different ones of the horizontallinear-shaped segment of the serpentine-shaped optical waveguide.

FIG. 15 shows an example optical path layout of an optical macro 305-x 7for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a Z-shaped optical waveguide 1501, inaccordance with some embodiments. The Z-shaped optical waveguide 1501includes a first horizontal (East-West oriented) segment 1501A, a firstcurved segment 1501B, a vertical (North-South oriented) segment 1501C, asecond curved segment 1501D, and a second horizontal (East-Westoriented) segment 1501E. In some embodiments, the first curved segment1501B curves around about 90 degrees from the first horizontal segment1501A to the vertical segment 1501C, vice-versa. In some embodiments,the second curved segment 1501D curves around about 90 degrees from thevertical segment 1501C to the second horizontal segment 1501E,vice-versa. In this manner, the vertical segment 1501C of the opticalwaveguide 1501 extends in a direction substantially perpendicular toeach of the first horizontal segment 1501A and the second horizontalsegment 1501E of the optical waveguide 1501. The first curved segment1501B and the second curved segment 1501D have mirrored orientationswith respect to each other (they have horizontally flipped orientationswith respect to each other). The first horizontal segment 1501A isoptically connected to a first optical port 1502A, and the secondhorizontal segment 1501E is optically connected to a second optical port1502B. The first optical port 1502A and the second optical port 1502Bare located on opposite sides of the optical macro 305-x 7. The firstoptical port 1502A is located on the left side (West side) of theoptical macro 305-x 7. The optical port 1502B is located on the rightside (East side) of the optical macro 305-x 7. In various embodiments,the first optical port 1502A is formed as a vertical optical gratingcoupler or a horizontal (edge) optical grating coupler. Also, in variousembodiments, the second optical port 1502B is formed as a verticaloptical grating coupler or a horizontal (edge) optical grating coupler.

In some embodiments, the first horizontal segment 1501A, the firstcurved segment 1501B, the vertical segment 1501C, the second curvedsegment 1501D, and the second horizontal segment 1501E of the opticalwaveguide 1501 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 1501A, the first curved segment 1501B, the verticalsegment 1501C, the second curved segment 1501D, and the secondhorizontal segment 1501E of the optical waveguide 1501 is/are formed ofa different material than one or more others of the first horizontalsegment 1501A, the first curved segment 1501B, the vertical segment1501C, the second curved segment 1501D, and the second horizontalsegment 1501E of the optical waveguide 1501, such that the opticalwaveguide 1501 is formed as a combination of materials, e.g., acombination of two or more of silicon, polysilicon, silicon nitride,and/or any other material suitable for use as an optical waveguide.Also, in some embodiments, each of the first horizontal segment 1501A,the first curved segment 1501B, the vertical segment 1501C, the secondcurved segment 1501D, and the second horizontal segment 1501E of theoptical waveguide 1501 is formed to have a substantially similarvertical cross-section shape. However, in some embodiments, any one ormore of the first horizontal segment 1501A, the first curved segment1501B, the vertical segment 1501C, the second curved segment 1501D, andthe second horizontal segment 1501E of the optical waveguide 1501 is/areformed to have a different vertical cross-section shape than one or moreothers of the first horizontal segment 1501A, the first curved segment1501B, the vertical segment 1501C, the second curved segment 1501D, andthe second horizontal segment 1501E of the optical waveguide 1501. Also,in some embodiments, any one or more of the first horizontal segment1501A, the first curved segment 1501B, the vertical segment 1501C, thesecond curved segment 1501D, and the second horizontal segment 1501E ofthe optical waveguide 1501 is/are formed to have a verticalcross-section shape that varies along its length in the direction oflight propagation through the optical waveguide 1501.

The optical macro 305-x 7 includes optical microring resonators 1503-1to 1503-X (where X is an integer greater than zero) that are opticallycoupled to the first horizontal segment 1501A of the Z-shaped opticalwaveguide 1501, such that light traveling through the optical waveguide1501 can be evanescently coupled into the optical microring resonators1503-1 to 1503-X, and such that light traveling through the opticalmicroring resonators 1503-1 to 1503-X can be evanescently coupled intothe optical waveguide 1501. The optical macro 305-x 7 also includesoptical microring resonators 1505-1 to 1505-Y (where Y is an integergreater than zero) that are optically coupled to the vertical segment1501C of the Z-shaped optical waveguide 1501, such that light travelingthrough the optical waveguide 1501 can be evanescently coupled into theoptical microring resonators 1505-1 to 1505-Y, and such that lighttraveling through the optical microring resonators 1505-1 to 1505-Y canbe evanescently coupled into the optical waveguide 1501. The opticalmacro 305-x 7 also includes optical microring resonators 1507-1 to1507-Z (where Z is an integer greater than zero) that are opticallycoupled to the second horizontal segment 1501E of the Z-shaped opticalwaveguide 1501, such that light traveling through the optical waveguide1501 can be evanescently coupled into the optical microring resonators1507-1 to 1507-Z, and such that light traveling through the opticalmicroring resonators 1507-1 to 1507-Z can be evanescently coupled intothe optical waveguide 1501.

In some embodiments, the optical microring resonators 1503-1 to 1503-X,1505-1 to 1505-Y, and 1507-1 to 1507-Z are positioned relative to theoptical waveguide 1501 such that a respective minimum separationdistance between each of the optical microring resonators 1503-1 to1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z and the optical waveguide1501 is substantially the same. However, in some embodiments, theoptical microring resonators 1503-1 to 1503-X, 1505-1 to 1505-Y, and1507-1 to 1507-Z are positioned relative to the optical waveguide 1501such that multiple different minimum separation distances exist betweendifferent ones of the optical microring resonators 1503-1 to 1503-X,1505-1 to 1505-Y, and 1507-1 to 1507-Z and the optical waveguide 1501.

In various embodiments, the optical microring resonators 1503-1 to1503-X are positioned at a substantially constant pitch(center-to-center spacing) with respect to each other. However, in otherembodiments, the optical microring resonators 1503-1 to 1503-X are notpositioned at a substantially constant pitch with respect to each other.In some embodiments, the pitch between adjacently positioned ones of theoptical microring resonators 1503-1 to 1503-X is set at a distance thatavoids evanescent coupling of light between the adjacently positionedones of the optical microring resonators 1503-1 to 1503-X. In someembodiments, the pitch between adjacently positioned ones of the opticalmicroring resonators 1503-1 to 1503-X is minimized while ensuring thatevanescent coupling of light does not occur between adjacentlypositioned ones of the optical microring resonators 1503-1 to 1503-X. Insome embodiments, the optical microring resonators 1503-1 to 1503-X donot optically couple to the same location along optical waveguide 1501in order to avoid optical intercoupling between different ones of theoptical microring resonators 1503-1 to 1503-X.

Also, in various embodiments, the optical microring resonators 1505-1 to1505-Y are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1505-1 to 1505-Y are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1505-1 to 1505-Y is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1505-1 to 1505-Y. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1505-1 to 1505-Y is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1505-1 to 1505-Y. In some embodiments, the opticalmicroring resonators 1505-1 to 1505-Y do not optically couple to thesame location along optical waveguide 1501 in order to avoid opticalintercoupling between different ones of the optical microring resonators1505-1 to 1505-Y.

Also, in various embodiments, the optical microring resonators 1507-1 to1507-Z are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1507-1 to 1507-Z are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1507-1 to 1507-Z is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1507-1 to 1507-Z. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1507-1 to 1507-Z is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1507-1 to 1507-Z. In some embodiments, the opticalmicroring resonators 1507-1 to 1507-Z do not optically couple to thesame location along optical waveguide 1501 in order to avoid opticalintercoupling between different ones of the optical microring resonators1507-1 to 1507-Z.

In some embodiments, each of the optical microring resonators 1503-1 to1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z has an outer diametergreater than zero and less than or equal to about 50 micrometers. Insome embodiments, each of the optical microring resonators 1503-1 to1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z has an outer diametergreater than zero and less than or equal to about 40 micrometers. Insome embodiments, each of the optical microring resonators 1503-1 to1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z has an outer diametergreater than zero and less than or equal to about 30 micrometers. Insome embodiments, each of the optical microring resonators 1503-1 to1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z has an outer diametergreater than zero and less than or equal to about 20 micrometers. Insome embodiments, each of the optical microring resonators 1503-1 to1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z has an outer diametergreater than zero and less than or equal to about 10 micrometers.

The optical microring resonators 1503-1 to 1503-X are interfaced withelectronic control circuitry 1509. In some embodiments, the electroniccontrol circuity 1509 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1503-1to 1503-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1501, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1509 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1503-1 to 1503-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1501 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1509 includes circuitry for directing one or more of themicroring resonators 1503-1 to 1503-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1501. In some embodiments, the electronic control circuity1509 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1503-1 to 1503-Xto enable thermal tuning of the one or more of the microring resonators1503-1 to 1503-X.

The optical microring resonators 1505-1 to 1505-Y are interfaced withelectronic control circuitry 1511. In some embodiments, the electroniccontrol circuity 1511 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1505-1to 1505-Y as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1501, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1511 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1505-1 to 1505-Y as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1501 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1511 includes circuitry for directing one or more of themicroring resonators 1505-1 to 1505-Y to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1501. In some embodiments, the electronic control circuity1511 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1505-1 to 1505-Yto enable thermal tuning of the one or more of the microring resonators1505-1 to 1505-Y.

The optical microring resonators 1507-1 to 1507-Z are interfaced withelectronic control circuitry 1513. In some embodiments, the electroniccontrol circuity 1513 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1507-1to 1507-Z as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1501, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1513 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1507-1 to 1507-Z as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1501 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1513 includes circuitry for directing one or more of themicroring resonators 1507-1 to 1507-Z to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1501. In some embodiments, the electronic control circuity1513 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1507-1 to 1507-Zto enable thermal tuning of the one or more of the microring resonators1507-1 to 1507-Z. Also, in some embodiments, the optical macro 305-x 7includes additional electronics to support operation of the opticalmacro 305-x 7, such as clock signal generation and transmissioncircuitry, I/Q signal generation circuitry, ILO circuitry, PI circuitry,TIA circuitry, signal EQ circuitry, and/or other types of circuitry forsupporting operation of the optical macro 305-x 7.

In some embodiments, the optical path layout of the optical macro 305-x7 is optimized by minimizing a length of the optical waveguide 1501within the optical macro 305-x 7. The length of the optical waveguide1501 within the optical macro 305-x 7 is minimized byreducing/constraining the pitch of the optical microring resonators1503-1 to 1503-X, 1505-1 to 1505-Y, and 1507-1 to 1507-Z. In someembodiments of the optical path layout of the optical macro 305-x 7 oneor more additional optical microring resonators are positioned along thefirst curved segment 1501B and/or the second curved segment 1501D, sothat the one or more additional optical microring resonators opticallycouple with the optical waveguide 1501. It should be understood that invarious embodiments the optical path layout of the optical macro 305-x 7can be modified so that vertical segment 1501C of the Z-shaped opticalwaveguide 1501 is replaced by a linear-shaped segment 1501C′ thatextends at a non-right angle (either than about 90 degrees or greaterthan about 90 degrees) with respect to each of the first horizontalsegment 1501A and the second horizontal segment 1501E of the Z-shapedoptical waveguide 1501. Moreover, in some embodiments, the firsthorizontal segment 1501A, the vertical segment 1501C, and/or the secondhorizontal segment 1501E of the Z-shaped optical waveguide 1501 havedifferent lengths, such that different numbers X, Y, and Z of theoptical microring resonators 1503-1 to 1503-X, 1505-1 to 1505-Y, and1507-1 to 1507-Z are positioned along different ones of the firsthorizontal segment 1501A, the vertical segment 1501C, and the secondhorizontal segment 1501E, respectively, of the optical waveguide 1501.

FIG. 16 shows an example optical path layout of an optical macro 305-x 8for data input/output to/from the TeraPHY optical I/O chiplet 107, wherethe optical path layout includes a hook-shaped optical waveguide 1601,in accordance with some embodiments. The optical waveguide 1601 includesa first horizontal (East-West oriented) segment 1601A, a first curvedsegment 1601B, a second horizontal (East-West oriented) segment 1601C, asecond curved segment 1601D, and a vertical segment (North-Southoriented) segment 1601E. In some embodiments, the first curved segment1601B curves around about 180 degrees from the first horizontal segment1601A to the second horizontal segment 1601C, vice-versa. In someembodiments, the second curved segment 1601D curves around about 90degrees from the second horizontal segment 1601C to the vertical segment1601E, vice-versa. The first horizontal segment 1601A is opticallyconnected to a first optical port 1602A. The vertical segment 1601E isoptically connected to a second optical port 1602B. The first opticalport 1602A and the second optical port 1602B are located on adjacentsides of the optical macro 305-x 8. The first optical port 1602A islocated on the left side (West side) of the optical macro 305-x 8, andthe optical port 1602B is located on the lower side (South side) of theoptical macro 305-x 8. In various embodiments, the first optical port1602A is formed as a vertical optical grating coupler or a horizontal(edge) optical grating coupler. Also, in various embodiments, the secondoptical port 1602B is formed as a vertical optical grating coupler or ahorizontal (edge) optical grating coupler.

In some embodiments, the first horizontal segment 1601A, the firstcurved segment 1601B, the second horizontal segment 1601C, the secondcurved segment 1601D, and the vertical segment 1601E of the opticalwaveguide 1601 are formed of a same material, such as silicon,polysilicon, silicon nitride, or any other material suitable for use asan optical waveguide. In some embodiments, any one or more of the firsthorizontal segment 1601A, the first curved segment 1601B, the secondhorizontal segment 1601C, the second curved segment 1601D, and thevertical segment 1601E of the optical waveguide 1601 is/are formed of adifferent material than one or more others of the first horizontalsegment 1601A, the first curved segment 1601B, the second horizontalsegment 1601C, the second curved segment 1601D, and the vertical segment1601E of the optical waveguide 1601, such that the optical waveguide1601 is formed as a combination of materials, e.g., a combination of twoor more of silicon, polysilicon, silicon nitride, and/or any othermaterial suitable for use as an optical waveguide. Also, in someembodiments, each of the first horizontal segment 1601A, the firstcurved segment 1601B, the second horizontal segment 1601C, the secondcurved segment 1601D, and the vertical segment 1601E of the opticalwaveguide 1601 is formed to have a substantially similar verticalcross-section shape. However, in some embodiments, any one or more ofthe first horizontal segment 1601A, the first curved segment 1601B, thesecond horizontal segment 1601C, the second curved segment 1601D, andthe vertical segment 1601E of the optical waveguide 1601 is/are formedto have a different vertical cross-section shape than one or more othersof the first horizontal segment 1601A, the first curved segment 1601B,the second horizontal segment 1601C, the second curved segment 1601D,and the vertical segment 1601E of the optical waveguide 1601. Also, insome embodiments, any one or more of the first horizontal segment 1601A,the first curved segment 1601B, the second horizontal segment 1601C, thesecond curved segment 1601D, and the vertical segment 1601E of theoptical waveguide 1601 is/are formed to have a vertical cross-sectionshape that varies along its length in the direction of light propagationthrough the optical waveguide 1601.

The optical macro 305-x 8 includes optical microring resonators 1603-1to 1603-X (where X is an integer greater than zero) that are opticallycoupled to the first horizontal segment 1601A of the hook-shaped opticalwaveguide 1601, such that light traveling through the optical waveguide1601 can be evanescently coupled into the optical microring resonators1603-1 to 1603-X, and such that light traveling through the opticalmicroring resonators 1603-1 to 1603-X can be evanescently coupled intothe optical waveguide 1601. The optical macro 305-x 8 also includesoptical microring resonators 1605-1 to 1605-Y (where Y is an integergreater than zero) that are optically coupled to the second horizontalsegment 1601C of the hook-shaped optical waveguide 1601, such that lighttraveling through the optical waveguide 1601 can be evanescently coupledinto the optical microring resonators 1605-1 to 1605-Y, and such thatlight traveling through the optical microring resonators 1605-1 to1605-Y can be evanescently coupled into the optical waveguide 1601.

The optical macro 305-x 8 shows a particular example of an opticallayout in which each of the optical microring resonators 1603-1 to1603-X and 1605-1 to 1605-Y is optically coupled to one of the twohorizontal segments 1601A and 1601C of the hook-shaped optical waveguide1601. In some embodiments, the optical microring resonators 1603-1 to1603-X and 1605-1 to 1605-Y are positioned relative to the opticalwaveguide 1601 such that a respective minimum separation distancebetween each of the optical microring resonators 1603-1 to 1603-X and1605-1 to 1605-Y and the optical waveguide 1601 is substantially thesame. However, in some embodiments, the optical microring resonators1603-1 to 1603-X and 1605-1 to 1605-Y are positioned relative to theoptical waveguide 1601 such that multiple different minimum separationdistances exist between different ones of the optical microringresonators 1603-1 to 1603-X and 1605-1 to 1605-Y and the opticalwaveguide 1601.

In various embodiments, the optical microring resonators 1603-1 to1603-X are positioned at a substantially constant pitch(center-to-center spacing) with respect to each other. However, in otherembodiments, the optical microring resonators 1603-1 to 1603-X are notpositioned at a substantially constant pitch with respect to each other.In some embodiments, the pitch between adjacently positioned ones of theoptical microring resonators 1603-1 to 1603-X is set at a distance thatavoids evanescent coupling of light between the adjacently positionedones of the optical microring resonators 1603-1 to 1603-X. In someembodiments, the pitch between adjacently positioned ones of the opticalmicroring resonators 1603-1 to 1603-X is minimized while ensuring thatevanescent coupling of light does not occur between adjacentlypositioned ones of the optical microring resonators 1603-1 to 1603-X. Insome embodiments, the optical microring resonators 1603-1 to 1603-X donot optically couple to the same location along optical waveguide 1601in order to avoid optical intercoupling between different ones of theoptical microring resonators 1603-1 to 1603-X.

Also, in various embodiments, the optical microring resonators 1605-1 to1605-Y are positioned at a substantially constant pitch with respect toeach other. However, in other embodiments, the optical microringresonators 1605-1 to 1605-Y are not positioned at a substantiallyconstant pitch with respect to each other. In some embodiments, thepitch between adjacently positioned ones of the optical microringresonators 1605-1 to 1605-Y is set at a distance that avoids evanescentcoupling of light between the adjacently positioned ones of the opticalmicroring resonators 1605-1 to 1605-Y. In some embodiments, the pitchbetween adjacently positioned ones of the optical microring resonators1605-1 to 1605-Y is minimized while ensuring that evanescent coupling oflight does not occur between adjacently positioned ones of the opticalmicroring resonators 1605-1 to 1605-Y. In some embodiments, the opticalmicroring resonators 1605-1 to 1605-Y do not optically couple to thesame location along optical waveguide 1601 in order to avoid opticalintercoupling between different ones of the optical microring resonators1605-1 to 1605-Y.

In some embodiments, each of the optical microring resonators 1603-1 to1603-X and 1605-1 to 1605-Y has an outer diameter greater than zero andless than or equal to about 50 micrometers. In some embodiments, each ofthe optical microring resonators 1603-1 to 1603-X and 1605-1 to 1605-Yhas an outer diameter greater than zero and less than or equal to about40 micrometers. In some embodiments, each of the optical microringresonators 1603-1 to 1603-X and 1605-1 to 1605-Y has an outer diametergreater than zero and less than or equal to about 30 micrometers. Insome embodiments, each of the optical microring resonators 1603-1 to1603-X and 1605-1 to 1605-Y has an outer diameter greater than zero andless than or equal to about 20 micrometers. In some embodiments, each ofthe optical microring resonators 1603-1 to 1603-X and 1605-1 to 1605-Yhas an outer diameter greater than zero and less than or equal to about10 micrometers.

The optical microring resonators 1603-1 to 1603-X are interfaced withelectronic control circuitry 1607. In some embodiments, the electroniccontrol circuity 1607 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1603-1to 1603-X as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1601, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1607 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1603-1 to 1603-X as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1601 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1607 includes circuitry for directing one or more of themicroring resonators 1603-1 to 1603-X to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1601. In some embodiments, the electronic control circuity1607 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1603-1 to 1603-Xto enable thermal tuning of the one or more of the microring resonators1603-1 to 1603-X.

The optical microring resonators 1605-1 to 1605-Y are interfaced withelectronic control circuitry 1609. In some embodiments, the electroniccontrol circuity 1609 includes transmit (Tx) slice circuitry forindependently controlling one or more of the microring resonators 1605-1to 1605-Y as an optical modulator to optically modulate light at a givenwavelength to generate a light stream at the given wavelength within theoptical waveguide 1601, where the light stream conveys digital data. Insome embodiments, the electronic control circuity 1609 includes receive(Rx) slice circuitry for independently controlling one or more of themicroring resonators 1605-1 to 1605-Y as an optical receiver, e.g.,photodetector, to detect a modulated light stream at a given wavelengthwithin the optical waveguide 1601 to enable generation of electricalsignals representing digital data conveyed by the modulated light streamat the given wavelength. In some embodiments, the electronic controlcircuity 1609 includes circuitry for directing one or more of themicroring resonators 1605-1 to 1605-Y to operate as an add/drop filterfor multiplexing/demultiplexing of optical signals within the opticalwaveguide 1601. In some embodiments, the electronic control circuity1609 includes circuitry for controlling heating devices respectivelyassociated with one or more of the microring resonators 1605-1 to 1605-Yto enable thermal tuning of the one or more of the microring resonators1605-1 to 1605-Y. Also, in some embodiments, the optical macro 305-x 8includes additional electronics to support operation of the opticalmacro 305-x 8, such as clock signal generation and transmissioncircuitry, I/Q signal generation circuitry, ILO circuitry, PI circuitry,TIA circuitry, signal EQ circuitry, and/or other types of circuitry forsupporting operation of the optical macro 305-x 8.

In some embodiments, the optical path layout of the optical macro 305-x8 is optimized by minimizing a length of the optical waveguide 1601within the optical macro 305-x 8. The length of the optical waveguide1601 within the optical macro 305-x 8 is minimized by having the opticalmicroring resonators 1603-1 to 1603-X and 1605-1 to 1605-Y respectivelypositioned along each of the first horizontal segment 1601A and thesecond horizontal segment 1601C of the optical waveguide 1601, andreducing/constraining the pitch of the optical microring resonators1603-1 to 1603-X and 1605-1 to 1605-Y. In some embodiments of theoptical path layout of the optical macro 305-x 8 one or more additionaloptical microring resonators are positioned along the first curvedsegment 1601B and/or the second curved segment 1601D, so that the one ormore additional optical microring resonators optically couple with theoptical waveguide 1601. It should be understood that in variousembodiments the optical path layout of the optical macro 305-x 8 can bemodified so that the hook-shaped optical waveguide 1601 becomes aserpentine-shaped optical waveguide that includes essentially any numberof horizontal linear-shaped segments and any number of curved segments,with essentially any number of optical microring resonators positionedalong the serpentine-shaped optical waveguide so as to optically couplewith the serpentine-shaped optical waveguide. Moreover, in someembodiments, the different horizontal linear-shaped segments and/orcurved segments of the serpentine-shaped optical waveguide can havedifferent lengths, such that different numbers of optical microringresonators are positioned along different ones of the horizontallinear-shaped segment of the serpentine-shaped optical waveguide.

Various embodiments are disclosed herein for an electro-optical chip,such as the TeraPHY optical I/O chiplet 107, that includes an opticalinput port located on a first side of the electro-optical chip and anoptical output port also located on the first side of theelectro-optical chip. The electro-optical chip also includes an opticalwaveguide having a first end optically connected to the optical inputport. The optical waveguide also has a second end optically connected tothe optical output port. In some embodiments, the optical waveguideextends through an optical macro, such as the optical macro 305-x. Theoptical waveguide includes a first segment extending in a firstdirection. The optical waveguide also includes a second segment thatextends from the first segment and that turns from the first directionto a second direction that is substantially opposite of the firstdirection. The optical waveguide also includes a third segment thatextends from the second segment in the second direction. The first,second, and third segments of the optical waveguide collectively form asubstantially U-shaped portion of the optical waveguide, such as theoptical waveguide 901 of FIG. 9. The electro-optical chip also includesa plurality of optical microring resonators positioned along the firstsegment of the optical waveguide. Each microring resonator of theplurality of optical microring resonators is optically coupled to adifferent location along the first segment of the optical waveguide. Insome embodiments, the plurality of optical microring resonators arepositioned in accordance with a substantially constant center-to-centerspacing (pitch) as measured in the first direction. In some embodiments,the plurality of optical microring resonators are positioned such thatat least two different center-to-center spacings as measured in thefirst direction exist between adjacent ones of the plurality of opticalmicroring resonators.

The electro-optical chip also includes electronic circuitry forcontrolling a resonant wavelength of each microring resonator of theplurality of optical microring resonators. In some embodiments, theelectro-optical chip includes electronic circuitry for controlling atleast some of the plurality of optical microring resonators to modulatelight at a specified wavelength traveling through the optical waveguidebetween the optical input and the optical output. In some embodiments,the electro-optical chip includes electronic circuitry for controllingat least some of the plurality of optical microring resonators tooperate as part of a respective photodetector device to detect light ofa specified wavelength traveling through the optical waveguide. In someembodiments, the plurality of optical microring resonators is a firstplurality of optical microring resonators, with the electro-optical chipalso including a second plurality of optical microring resonatorspositioned along the third segment of the optical waveguide. Eachmicroring resonator of the second plurality of optical microringresonators is optically coupled to a different location along the thirdsegment of the optical waveguide. In some embodiments, the secondplurality of optical microring resonators are positioned in accordancewith a substantially constant center-to-center spacing (pitch) asmeasured in the second direction. In some embodiments, the secondplurality of optical microring resonators are positioned such that atleast two different center-to-center spacings as measured in the seconddirection exist between adjacent ones of the second plurality of opticalmicroring resonators. The electro-optical chip also includes electroniccircuitry for controlling a resonant wavelength of each microringresonator of the second plurality of optical microring resonators. Insome embodiments, the electro-optical chip includes electronic circuitryfor controlling at least some of the second plurality of opticalmicroring resonators to modulate light at a specified wavelengthtraveling through the optical waveguide between the optical input andthe optical output. In some embodiments, the electro-optical chipincludes electronic circuitry for controlling at least some of thesecond plurality of optical microring resonators to operate as part of arespective photodetector device to detect light of a specifiedwavelength traveling through the optical waveguide.

In some embodiments, the U-shaped portion of the optical waveguidedelineates a first region and a second region of the electro-opticalchip, where the first region is partially circumscribed by the U-shapedportion of the optical waveguide, and where the second region is locatedon an opposite side of the U-shaped portion of the optical waveguidefrom the first region. In some embodiments, each of the above-mentionedfirst and second pluralities of optical microring resonators ispositioned within the second region. In some embodiments, the electroniccircuitry for controlling the resonant wavelength of each microringresonator of the first plurality of optical microring resonators isformed within the second region alongside the first plurality of opticalmicroring resonators. Also, in some embodiments, the electroniccircuitry for controlling the resonant wavelength of each microringresonator of the second plurality of optical microring resonators isformed within the second region alongside the second plurality ofoptical microring resonators.

In some embodiments, the electro-optical chip includes a third pluralityof optical microring resonators positioned along the second segment ofthe optical waveguide. Each microring resonator of the third pluralityof optical microring resonators is optically coupled to a differentlocation along the second segment of the optical waveguide. In someembodiments, the third plurality of optical microring resonators arepositioned in accordance with a substantially constant center-to-centerspacing (pitch) as measured in a third direction extending substantiallyperpendicular to both the first and second directions. In someembodiments, the third plurality of optical microring resonators arepositioned such that at least two different center-to-center spacings asmeasured in the third direction exist between adjacent ones of the thirdplurality of optical microring resonators. In some embodiments, theelectro-optical chip includes electronic circuitry for controlling aresonant wavelength of each microring resonator of the third pluralityof optical microring resonators. In some embodiments, theelectro-optical chip includes electronic circuitry for controlling atleast some of the third plurality of optical microring resonators tomodulate light at a specified wavelength traveling through the opticalwaveguide between the optical input and the optical output. In someembodiments, the electro-optical chip includes electronic circuitry forcontrolling at least some of the third plurality of optical microringresonators to operate as part of a respective photodetector device todetect light of a specified wavelength traveling through the opticalwaveguide.

In some embodiments, the substantially U-shaped portion of the opticalwaveguide delineates a first region and a second region of theelectro-optical chip, where the first region is partially circumscribedby the U-shaped portion of the optical waveguide, and where the secondregion is located on an opposite side of the U-shaped portion of theoptical waveguide from the first region, and where each of the first,second, and third pluralities of optical microring resonators ispositioned within the second region. In some embodiments, the electroniccircuitry for controlling the resonant wavelength of each microringresonator of the first plurality of optical microring resonators isformed within the second region alongside the first plurality of opticalmicroring resonators. Also, in these embodiments, the electroniccircuitry for controlling the resonant wavelength of each microringresonator of the second plurality of optical microring resonators isformed within the second region alongside the second plurality ofoptical microring resonators. Also, in these embodiments, the electroniccircuitry for controlling the resonant wavelength of each microringresonator of the third plurality of optical microring resonators isformed within the second region alongside the third plurality of opticalmicroring resonators.

Various embodiments are disclosed herein for an electro-optical chip,such as the TeraPHY optical 110 chiplet 107, that includes an opticalinput port located on a first side of the electro-optical chip and anoptical output port also located on the first side of theelectro-optical chip. The electro-optical chip also includes an opticalwaveguide having a first end optically connected to the optical inputport. The optical waveguide also has a second end optically connected tothe optical output port. In some embodiments, the optical waveguideextends through an optical macro, such as the optical macro 305-x. Theoptical waveguide includes: 1) a first segment extending in a firstdirection, 2) a second segment that extends from the first segment andthat turns from the first direction to a second direction that issubstantially perpendicular to the first direction, 3) a third segmentthat extends from the second segment in the second direction, 4) afourth segment that extends from the third segment and that turns fromthe second direction to a third direction that is substantially oppositeof the first direction, and 5) a fifth segment that extends from thefourth segment in the third direction, where the first, second, third,fourth, and fifth segments collectively form a substantially C-shapedportion of the optical waveguide, such as the optical waveguides 1001,1101, and 1201 of FIGS. 10, 11, and 12, respectively. Theelectro-optical chip also includes a plurality of optical microringresonators positioned along the third segment of the optical waveguide.Each microring resonator of the plurality of optical microringresonators is optically coupled to a different location along the thirdsegment of the optical waveguide. In some embodiments, the plurality ofoptical microring resonators are positioned in accordance with asubstantially constant center-to-center spacing (pitch) as measured inthe second direction. In some embodiments, the plurality of opticalmicroring resonators are positioned such that at least two differentcenter-to-center spacings as measured in the second direction existbetween adjacent ones of the plurality of optical microring resonators.

The electro-optical chip also includes electronic circuitry forcontrolling a resonant wavelength of each microring resonator of theplurality of optical microring resonators positioned along the thirdsegment of the optical waveguide. In some embodiments, theelectro-optical chip includes electronic circuitry for controlling atleast some of the plurality of optical microring resonators to modulatelight at a specified wavelength traveling through the optical waveguidebetween the optical input and the optical output. In some embodiments,the electro-optical chip includes electronic circuitry for controllingat least some of the plurality of optical microring resonators tooperate as a respective photodetector device to detect light of aspecified wavelength traveling through the optical waveguide. In someembodiments, the substantially C-shaped portion of the optical waveguidedelineates a first region and a second region of the electro-opticalchip, where the first region is partially circumscribed by the C-shapedportion of the optical waveguide, and where the second region is locatedon an opposite side of the C-shaped portion of the optical waveguidefrom the first region. In some embodiments, the plurality of opticalmicroring resonators positioned along the third segment of the opticalwaveguide is a first plurality of optical microring resonatorspositioned within the second region. In some embodiments, theelectro-optical chip includes a second plurality of optical microringresonators positioned along the third segment of the optical waveguidewithin the first region. In some embodiments, each microring resonatorof the first and second pluralities of optical microring resonators isoptically coupled to a different location along the third segment of theoptical waveguide. In some embodiments, the second plurality of opticalmicroring resonators are positioned in accordance with a substantiallyconstant center-to-center spacing (pitch) as measured in the seconddirection. In some embodiments, the second plurality of opticalmicroring resonators are positioned such that at least two differentcenter-to-center spacings as measured in the second direction existbetween adjacent ones of the second plurality of optical microringresonators.

In some embodiments, the electro-optical chip includes electroniccircuitry for controlling a resonant wavelength of each microringresonator of the second plurality of optical microring resonators. Insome embodiments, the electro-optical chip includes electronic circuitryfor controlling at least some of the second plurality of opticalmicroring resonators to modulate light at a specified wavelengthtraveling through the optical waveguide between the optical input andthe optical output. In some embodiments, the electro-optical chipincludes electronic circuitry for controlling at least some of thesecond plurality of optical microring resonators to operate as arespective photodetector device to detect light of a specifiedwavelength traveling through the optical waveguide. In some embodiments,the electronic circuitry for controlling the resonant wavelength of eachmicroring resonator of the first plurality of optical microringresonators is formed within the second region alongside the firstplurality of optical microring resonators, and the electronic circuitryfor controlling the resonant wavelength of each microring resonator ofthe second plurality of optical microring resonators is formed withinthe first region alongside the second plurality of optical microringresonators.

Various embodiments are disclosed herein for an electro-optical chip,such as the TeraPHY optical I/O chiplet 107, that includes an opticalinput port located on a first side of the electro-optical chip and anoptical output port also located on a second side of the electro-opticalchip. The electro-optical chip also includes an optical waveguide havinga first end optically connected to the optical input port. The opticalwaveguide also has a second end optically connected to the opticaloutput port. In some embodiments, the optical waveguide extends throughan optical macro, such as the optical macro 305-x. In variousembodiments, the optical waveguide is configured as either of theoptical waveguides 1301, 1401, 1501, and 1601 of FIGS. 13, 14, 15, and16, respectively. The electro-optical chip also includes a plurality ofoptical microring resonators positioned along the optical waveguide.Each microring resonator of the plurality of optical microringresonators is optically coupled to a different location along theoptical waveguide. The electro-optical chip also includes electroniccircuitry formed alongside the plurality of optical microring resonatorsfor controlling a resonant wavelength of each microring resonator of theplurality of optical microring resonators. In some embodiments, thefirst and second sides of the electro-optical chip corresponding to theoptical input port and the optical output port, respectively, areopposite sides of the electro-optical chip. In some embodiments, thefirst and second sides of the electro-optical chip corresponding to theoptical input port and the optical output port, respectively, areadjacent sides of the electro-optical chip.

In some embodiments, the optical waveguide includes: 1) a first segmentextending in a first direction, 2) a second segment that extends fromthe first segment and that turns from the first direction to a seconddirection different from the first direction, 3) a third segment thatextends from the second segment in the second direction, 4) a fourthsegment that extends from the third segment and that turns from thesecond direction back to the first direction, and 5) a fifth segmentthat extends from the fourth segment in the first direction. In someembodiments, the second direction is about 180 degrees offset from thefirst direction. In some embodiments, the second direction is about 90degrees offset from the first direction. In some embodiments, theplurality of optical microring resonators is a first plurality ofoptical microring resonators positioned along the first segment of theoptical waveguide. In some embodiments, the electro-optical chipincludes a second plurality of optical microring resonators positionedalong the third segment of the optical waveguide and between the firstand third segments of the optical waveguide, where each microringresonator of the second plurality of optical microring resonators isoptically coupled to a different location along the third segment of theoptical waveguide. In some embodiments, the electro-optical chip alsoincludes electronic circuitry formed alongside the second plurality ofoptical microring resonators for controlling a resonant wavelength ofeach microring resonator of the second plurality of optical microringresonators. In some embodiments, the electro-optical chip includes athird plurality of optical microring resonators positioned along thefifth segment of the optical waveguide and between the third and fifthsegments of the optical waveguide, where each microring resonator of thethird plurality of optical microring resonators is optically coupled toa different location along the fifth segment of the optical waveguide.In some embodiments, the electro-optical chip includes electroniccircuitry formed alongside the third plurality of optical microringresonators for controlling a resonant wavelength of each microringresonator of the third plurality of optical microring resonators.

In some embodiments, the optical waveguide includes: 1) a first segmentextending in a first direction, 2) a second segment that extends fromthe first segment and that turns from the first direction to a seconddirection different from the first direction, 3) a third segment thatextends from the second segment in the second direction, 4) a fourthsegment that extends from the third segment and that turns from thesecond direction to a third direction different from both the first andsecond directions, and 5) a fifth segment that extends from the fourthsegment in the third direction. In some embodiments, the seconddirection is about 180 degrees offset from the first direction, and thethird direction is about 90 degrees offset from the second direction. Insome embodiments, the plurality of optical microring resonators is afirst plurality of optical microring resonators positioned along thefirst segment of the optical waveguide. In some embodiments, theelectro-optical chip includes a second plurality of optical microringresonators positioned along the third segment of the optical waveguideand between the first and third segments of the optical waveguide, whereeach microring resonator of the second plurality of optical microringresonators is optically coupled to a different location along the thirdsegment of the optical waveguide. In some embodiments, theelectro-optical chip includes electronic circuitry formed alongside thesecond plurality of optical microring resonators for controlling aresonant wavelength of each microring resonator of the second pluralityof optical microring resonators.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

Although the foregoing disclosure includes some detail for purposes ofclarity of understanding, it will be apparent that certain changes andmodifications can be practiced within the scope of the appended claims.For example, it should be understood that one or more features from anyembodiment disclosed herein may be combined with one or more features ofany other embodiment disclosed herein. Accordingly, the presentembodiments are to be considered as illustrative and not restrictive,and what is claimed is not to be limited to the details given herein,but may be modified within the scope and equivalents of the describedembodiments.

What is claimed is:
 1. An electro-optical chip, comprising: an opticalinput port located on a first side of the electro-optical chip; anoptical output port located on the first side of the electro-opticalchip; an optical waveguide having a first end optically connected to theoptical input port, the optical waveguide having a second end opticallyconnected to the optical output port, the optical waveguide including afirst segment extending in a first direction, a second segment thatextends from the first segment and that turns from the first directionto a second direction that is substantially opposite of the firstdirection, and a third segment that extends from the second segment inthe second direction, wherein the first, second, and third segmentscollectively form a substantially U-shaped portion of the opticalwaveguide; a plurality of optical microring resonators positioned alongthe first segment of the optical waveguide, each microring resonator ofthe plurality of optical microring resonators optically coupled to adifferent location along the first segment of the optical waveguide; andelectronic circuitry for controlling a resonant wavelength of eachmicroring resonator of the plurality of optical microring resonators. 2.The electro-optical chip as recited in claim 1, further comprising:electronic circuitry for controlling at least some of the plurality ofoptical microring resonators to modulate light at a specified wavelengthtraveling through the optical waveguide between the optical input andthe optical output.
 3. The electro-optical chip as recited in claim 1,further comprising: electronic circuitry for controlling at least someof the plurality of optical microring resonators to operate as part of arespective photodetector device to detect light of a specifiedwavelength traveling through the optical waveguide.
 4. Theelectro-optical chip as recited in claim 1, wherein the plurality ofoptical microring resonators is a first plurality of optical microringresonators, the electro-optical chip including a second plurality ofoptical microring resonators positioned along the third segment of theoptical waveguide, each microring resonator of the second plurality ofoptical microring resonators optically coupled to a different locationalong the third segment of the optical waveguide, the electro-opticalchip including electronic circuitry for controlling a resonantwavelength of each microring resonator of the second plurality ofoptical microring resonators.
 5. The electro-optical chip as recited inclaim 4, further comprising: electronic circuitry for controlling atleast some of the second plurality of optical microring resonators tomodulate light at a specified wavelength traveling through the opticalwaveguide between the optical input and the optical output.
 6. Theelectro-optical chip as recited in claim 4, further comprising:electronic circuitry for controlling at least some of the secondplurality of optical microring resonators to operate as part of arespective photodetector device to detect light of a specifiedwavelength traveling through the optical waveguide.
 7. Theelectro-optical chip as recited in claim 4, wherein the substantiallyU-shaped portion of the optical waveguide delineates a first region anda second region of the electro-optical chip, wherein the first region ispartially circumscribed by the U-shaped portion of the optical waveguideand the second region is located on an opposite side of the U-shapedportion of the optical waveguide from the first region, wherein each ofthe first and second pluralities of optical microring resonators ispositioned within the second region.
 8. The electro-optical chip asrecited in claim 7, wherein the electronic circuitry for controlling theresonant wavelength of each microring resonator of the first pluralityof optical microring resonators is formed within the second regionalongside the first plurality of optical microring resonators, andwherein the electronic circuitry for controlling the resonant wavelengthof each microring resonator of the second plurality of optical microringresonators is formed within the second region alongside the secondplurality of optical microring resonators.
 9. The electro-optical chipas recited in claim 4, further comprising: a third plurality of opticalmicroring resonators positioned along the second segment of the opticalwaveguide, each microring resonator of the third plurality of opticalmicroring resonators optically coupled to a different location along thesecond segment of the optical waveguide; and electronic circuitry forcontrolling a resonant wavelength of each microring resonator of thethird plurality of optical microring resonators.
 10. The electro-opticalchip as recited in claim 9, further comprising: electronic circuitry forcontrolling at least some of the third plurality of optical microringresonators to modulate light at a specified wavelength traveling throughthe optical waveguide between the optical input and the optical output.11. The electro-optical chip as recited in claim 9, further comprising:electronic circuitry for controlling at least some of the thirdplurality of optical microring resonators to operate as part of arespective photodetector device to detect light of a specifiedwavelength traveling through the optical waveguide.
 12. Theelectro-optical chip as recited in claim 9, wherein the substantiallyU-shaped portion of the optical waveguide delineates a first region anda second region of the electro-optical chip, wherein the first region ispartially circumscribed by the U-shaped portion of the optical waveguideand the second region is located on an opposite side of the U-shapedportion of the optical waveguide from the first region, wherein each ofthe first, second, and third pluralities of optical microring resonatorsis positioned within the second region.
 13. The electro-optical chip asrecited in claim 12, wherein the electronic circuitry for controllingthe resonant wavelength of each microring resonator of the firstplurality of optical microring resonators is formed within the secondregion alongside the first plurality of optical microring resonators,and wherein the electronic circuitry for controlling the resonantwavelength of each microring resonator of the second plurality ofoptical microring resonators is formed within the second regionalongside the second plurality of optical microring resonators, andwherein the electronic circuitry for controlling the resonant wavelengthof each microring resonator of the third plurality of optical microringresonators is formed within the second region alongside the thirdplurality of optical microring resonators.
 14. An electro-optical chip,comprising: an optical input port located on a first side of theelectro-optical chip; an optical output port located on the first sideof the electro-optical chip; an optical waveguide having a first endoptically connected to the optical input port, the optical waveguidehaving a second end optically connected to the optical output port, theoptical waveguide including a first segment extending in a firstdirection, a second segment that extends from the first segment and thatturns from the first direction to a second direction that issubstantially perpendicular to the first direction, a third segment thatextends from the second segment in the second direction, a fourthsegment that extends from the third segment and that turns from thesecond direction to a third direction that is substantially opposite ofthe first direction, and a fifth segment that extends from the fourthsegment in the third direction, wherein the first, second, third,fourth, and fifth segments collectively form a substantially C-shapedportion of the optical waveguide; a plurality of optical microringresonators positioned along the third segment of the optical waveguide,each microring resonator of the plurality of optical microringresonators optically coupled to a different location along the thirdsegment of the optical waveguide; and electronic circuitry forcontrolling a resonant wavelength of each microring resonator of theplurality of optical microring resonators.
 15. The electro-optical chipas recited in claim 14, further comprising: electronic circuitry forcontrolling at least some of the plurality of optical microringresonators to modulate light at a specified wavelength traveling throughthe optical waveguide between the optical input and the optical output.16. The electro-optical chip as recited in claim 14, further comprising:electronic circuitry for controlling at least some of the plurality ofoptical microring resonators to operate as a respective photodetectordevice to detect light of a specified wavelength traveling through theoptical waveguide.
 17. The electro-optical chip as recited in claim 14,wherein the substantially C-shaped portion of the optical waveguidedelineates a first region and a second region of the electro-opticalchip, wherein the first region is partially circumscribed by theC-shaped portion of the optical waveguide and the second region islocated on an opposite side of the C-shaped portion of the opticalwaveguide from the first region, wherein the plurality of opticalmicroring resonators is a first plurality of optical microringresonators positioned within the second region, the electro-optical chipincluding a second plurality of optical microring resonators positionedalong the third segment of the optical waveguide within the firstregion, each microring resonator of the first and second pluralities ofoptical microring resonators optically coupled to a different locationalong the third segment of the optical waveguide, the electro-opticalchip including electronic circuitry for controlling a resonantwavelength of each microring resonator of the second plurality ofoptical microring resonators.
 18. The electro-optical chip as recited inclaim 17, further comprising: electronic circuitry for controlling atleast some of the second plurality of optical microring resonators tomodulate light at a specified wavelength traveling through the opticalwaveguide between the optical input and the optical output.
 19. Theelectro-optical chip as recited in claim 17, further comprising:electronic circuitry for controlling at least some of the secondplurality of optical microring resonators to operate as a respectivephotodetector device to detect light of a specified wavelength travelingthrough the optical waveguide.
 20. The electro-optical chip as recitedin claim 17, wherein the electronic circuitry for controlling theresonant wavelength of each microring resonator of the first pluralityof optical microring resonators is formed within the second regionalongside the first plurality of optical microring resonators, andwherein the electronic circuitry for controlling the resonant wavelengthof each microring resonator of the second plurality of optical microringresonators is formed within the first region alongside the secondplurality of optical microring resonators.
 21. An electro-optical chip,comprising: an optical input port located on a first side of theelectro-optical chip; an optical output port located on a second side ofthe electro-optical chip; an optical waveguide having a first endoptically connected to the optical input port, the optical waveguidehaving a second end optically connected to the optical output port; aplurality of optical microring resonators positioned along the opticalwaveguide, each microring resonator of the plurality of opticalmicroring resonators optically coupled to a different location along theoptical waveguide; and electronic circuitry formed alongside theplurality of optical microring resonators for controlling a resonantwavelength of each microring resonator of the plurality of opticalmicroring resonators.
 22. The electro-optical chip as recited in claim21, wherein the first and second sides of the electro-optical chip areopposite sides of the electro-optical chip.
 23. The electro-optical chipas recited in claim 21, wherein the first and second sides of theelectro-optical chip are adjacent sides of the electro-optical chip. 24.The electro-optical chip as recited in claim 21, wherein the opticalwaveguide includes a first segment extending in a first direction, asecond segment that extends from the first segment and that turns fromthe first direction to a second direction different from the firstdirection, a third segment that extends from the second segment in thesecond direction, a fourth segment that extends from the third segmentand that turns from the second direction back to the first direction,and a fifth segment that extends from the fourth segment in the firstdirection, wherein the plurality of optical microring resonators is afirst plurality of optical microring resonators positioned along thefirst segment of the optical waveguide.
 25. The electro-optical chip asrecited in claim 24, further comprising: a second plurality of opticalmicroring resonators positioned along the third segment of the opticalwaveguide and between the first and third segments of the opticalwaveguide, each microring resonator of the second plurality of opticalmicroring resonators optically coupled to a different location along thethird segment of the optical waveguide; electronic circuitry formedalongside the second plurality of optical microring resonators forcontrolling a resonant wavelength of each microring resonator of thesecond plurality of optical microring resonators; a third plurality ofoptical microring resonators positioned along the fifth segment of theoptical waveguide and between the third and fifth segments of theoptical waveguide, each microring resonator of the third plurality ofoptical microring resonators optically coupled to a different locationalong the fifth segment of the optical waveguide; and electroniccircuitry formed alongside the third plurality of optical microringresonators for controlling a resonant wavelength of each microringresonator of the third plurality of optical microring resonators. 26.The electro-optical chip as recited in claim 24, wherein the seconddirection is about 180 degrees offset from the first direction.
 27. Theelectro-optical chip as recited in claim 24, wherein the seconddirection is about 90 degrees offset from the first direction.
 28. Theelectro-optical chip as recited in claim 21, wherein the opticalwaveguide includes a first segment extending in a first direction, asecond segment that extends from the first segment and that turns fromthe first direction to a second direction different from the firstdirection, a third segment that extends from the second segment in thesecond direction, a fourth segment that extends from the third segmentand that turns from the second direction to a third direction differentfrom both the first and second directions, and a fifth segment thatextends from the fourth segment in the third direction, wherein theplurality of optical microring resonators is a first plurality ofoptical microring resonators positioned along the first segment of theoptical waveguide.
 29. The electro-optical chip as recited in claim 28,further comprising: a second plurality of optical microring resonatorspositioned along the third segment of the optical waveguide and betweenthe first and third segments of the optical waveguide, each microringresonator of the second plurality of optical microring resonatorsoptically coupled to a different location along the third segment of theoptical waveguide; electronic circuitry formed alongside the secondplurality of optical microring resonators for controlling a resonantwavelength of each microring resonator of the second plurality ofoptical microring resonators.
 30. The electro-optical chip as recited inclaim 28, wherein the second direction is about 180 degrees offset fromthe first direction, and wherein the third direction is about 90 degreesoffset from the second direction.